German Chancellor Angela Merkel visited Russian opposition politician Alexei Navalny while he was undergoing treatment in a Berlin hospital for poisoning, Navalny said on Monday.

News of the meeting is likely to annoy Moscow, which rejects the finding of German, French and Swedish experts that Navalny was poisoned with a nerve agent in Russia in August.

Russia has repeatedly criticised Berlin for what Moscow says is a failure to share information on the case.

Confirming a report by German news magazine Der Spiegel, Navalny wrote on Twitter that it was “a private meeting and conversation with the family.”

He added: “I am very grateful to Chancellor Merkel for visiting me in hospital.”

A spokesman for Merkel earlier declined to comment on the Der Spiegel report.

The Navalny case has further worsened relations between Moscow and a number of western countries.

Merkel has faced calls to halt the nearly-completed Nord Stream 2 pipeline bringing Russian gas to Germany.

Navalny was flown from Russia to Berlin in August after falling ill on a domestic flight.

He received treatment in the Charite hospital for 32 days before being discharged last week.