Ex minister water and energy in Cameroon was Arrested in Nigeria and flown home on Thursday, a police source and local media revealed, amid a crackdown on high-level corruption. Basile Atangana Kouna was removed from his ministerial position during President Paul Biya’s March 2 cabinet reshuffle.

He had already been ordered the month before not to leave the country.

“Atangana Kouna is in Cameroon. He was arrested in Nigeria and sent back to Cameroon. He arrived this evening,” one police source, who claimed anonymity told Reuters.

Vision 4, a private television channel considered allied to Biya, reported that the former minister arrived at the international airport in the capital Yaounde at 6:20 pm (1720 GMT) escorted by police officers.

Another channel, Canal 2 International, also reported his arrest in Nigeria and subsequent extradition back to Cameroon.

Cameroon’s government spokesman was not immediately reachable for comment. Neither were officials in neighbouring Nigeria.

It was not clear what charges Atangana Kouna was facing, but there was speculation on Thursday that he was arrested as part of an anti-corruption drive known as Operation Sparrowhawk.

Three men  a former Ministry of Public Works official, the head of a state company, and the ex-rector of the University of Douala – were arrested as part of the operation earlier this week.

Cameroon’s oil wealth has spawned a sprawling political patronage system fueled by revenues from crude exports. Transparency International ranked it 153 out of 180 countries on its annual corruption perceptions index.

Biya has ruled virtually by decree since taking over from a retiring predecessor in 1982 and then winning an election with 99.98 percent of the vote a year later.

Biya, 85 is expected to again seek re-election in presidential polls later this year, but he is currently facing some of the biggest challenges to his 35-year rule.

Cameroon’s oil-dependent economy has been crippled by low crude prices.