President Xi Jinping of China, traveling to Africa for the first time in five years, pledged greater cooperation with South Africa to enhance the voice of poor nations, and commended developing countries for “shaking off the yoke of colonialism.”

And on Wednesday, he held talks with the leaders of the BRICS, a club of emerging nations, where he also called for members to “accelerate” its expansion to serve as a counterweight to the West.

“At present, the Cold War mentality is lingering, and the geopolitical situation is grim,” Mr. Xi said on Wednesday. The grouping, he continued, should “bring more countries into the BRICS family so as to pool our strength, pool our wisdom to make global governance more just and equitable.”

On his visit to South Africa this week for the BRICS meetings, Mr. Xi has sought to cast himself as a leader of the developing world. Mr. Xi kicked off his four-day trip on Tuesday with a state visit and was received with an honor guard and a 21-gun salute.

For China, the reception in Pretoria reinforced the message Beijing hopes to send to audiences both at home and abroad: that China’s offer of an alternative to the U.S.-led global order has ample purchase outside the exclusive club of the developed countries. That has grown increasingly important to China. Its support for Russia and its aggressive posture on issues like the status of Taiwan, the self-governed island Beijing claims as its territory, has alienated it from countries in North America, Europe and Asia.

“For Xi, the goal is to try to discredit the West and show that there is an alternative out there,” said Eric Olander, the chief editor of The China-Global South Project website. “He’s trying to tap into this incredible well of grievance and frustration among many Global South countries over what they perceive as this massive duplicity and hypocrisy on the part of rich countries.”

That frustration has been driven in recent years by unfulfilled promises by developed countries to deliver Covid-19 vaccines to poorer countries and the feeling that not enough is being done about soaring food and energy prices.

In a meeting with President Cyril Ramaphosa of South Africa on Tuesday, Mr. Xi said China and African countries should work more closely to address “changes and chaos” in the world — imagery Mr. Xi has used to describe intensifying competition from Washington.

Africa is an emerging battleground for global influence. Beijing has poured billions of dollars in loans, aid and investment in countries that have long been ignored by the West. The result of that outreach has been diplomatic support in international organizations like the United Nations and access to critical minerals needed to power growing industries like electric vehicles.

In more prosperous times, China’s spending spree in Africa saw highways and dams spring up in many African countries. But these projects came with crippling debt in countries like Zambia and Angola, both of which owe billions of dollars to Chinese state-owned banks. While China has restructured bilateral debt with countries like Ethiopia and Zambia, analysts say this covered only a fraction of what is owed. (Other analysts note that African governments owe much more to Western creditors than China.)

But the main highlight of Mr. Xi’s trip has been the summit in Johannesburg of the BRICS group of nations — named for its members, Brazil, Russia, India, China and South Africa — as Beijing seeks to increase its sway.

The Chinese leader took aim at the United States on Wednesday, while not mentioning it by name, calling on BRICS nations to “oppose decoupling and supply chain disruption” — a reference to the Biden administration’s trade restrictions targeting China on national security grounds.

A day earlier, Mr. Xi warned of bloc confrontation and called on nations not to “sleepwalk into the abyss of a new cold war,” in a speech that was read by China’s commerce minister, Wang Wentao, for undisclosed reasons.

“Should we embrace prosperity, openness and inclusiveness, or allow hegemonic and bullying acts to throw us into depression?” the speech read.

By contrast, Mr. Xi portrayed China as a force for stability and pointed to vague, loftily worded initiatives around development and security that analysts say are aimed at weakening the spread of Western liberal values and the influence of forums like the North Atlantic Treaty Organization.

In some ways, the summit in Johannesburg has taken on the characteristics of an official Chinese event, where media access is tightly controlled. Though hundreds of journalists attended the summit, only reporters with state-approved news outlets were permitted to enter the room where leaders gave their speeches.

A scheduled news briefing following the leaders’ speeches on Wednesday was abruptly canceled. Mr. Ramaphosa said it was so that journalists could “go and rest.” (Mr. Xi, it should be noted, is not the only BRICS leader who does not take questions from the media; Prime Minister Narendra Modi of India, too, rarely directly fields live questions from the press.)

The summit’s official attendees do not come only from the group’s five member countries. They include nations aligned with China, such as Iran, and others that profess nonalignment and are looking to hedge between Beijing and Washington, such as Indonesia and Saudi Arabia.

One major measure of success for Mr. Xi’s visit will be if the grouping adds more members. China is in favor of expansion to increase the group’s clout and, by extension, its own global standing. India and Brazil, on the other hand, are more reluctant to add members that might tilt the group more steadily toward China and make BRICS anti-Western.

At the meeting on Wednesday, the leaders sought to project a common position. Warnings against a return to the Cold War were a common refrain. Several leaders criticized the United Nations Security Council for what they described as its failures to bring an end to Russia’s war in Ukraine — while avoiding any criticism of President Vladimir V. Putin of Russia, a BRICS leader, for the invasion.

Mr. Modi said he supported expansion through consensus. It remains to be seen whether the group can agree on what entry criteria new countries would need to meet.

President Luiz Inácio Lula da Silva of Brazil expressed support for a common BRICS currency to reduce the group’s vulnerabilities to the dominance of the U.S. dollar in trade.

Mr. Putin, who spoke remotely over a video link because he is wanted for war crimes under a warrant issued by the International Criminal Court, again blamed Western countries for his war in Ukraine. He said Russia would assume chairmanship of BRICS next year and host a summit in the city of Kazan in October 2024.

South Africa, chafing against pressure from the West, has tried to stake the middle ground but has been pulled closer by China and Russia. It is also keen to position itself as a voice for emerging nations, especially those in Africa.

“We are grateful for the support and friendship that China has provided as we have worked to rebuild and transform our country after the devastation of apartheid,” Mr. Ramaphosa told Mr. Xi as he greeted him on Tuesday.

South Africa is China’s largest trading partner in Africa, and it serves as a key transit point for commodities exported from other countries on the continent to China.

Beijing also maintains deep ties with Mr. Ramaphosa’s African National Congress, even helping to establish an academy for young leaders. China has committed to helping South Africa repair its dilapidated national electricity grid and has had state energy companies visit South Africa during Mr. Xi’s state visit.

Mr. Xi has received fawning coverage in the Chinese state media over the visit. But the outreach to Africa comes as China is grappling with a housing crisis and slowing economic growth, problems that could diminish how much Beijing can spend on foreign aid and development.

“China as a whole is running out of money, particularly foreign exchange,” said Willy Lam, an analyst of Chinese politics who is a senior fellow at Jamestown Foundation, a research institute in Washington. “This has been a big impediment to Beijing’s plans to extend its influence in the developing world.”

Olivia Wang and Matthew Mpoke Bigg contributed reporting.