The CEO of Russia’s oil behemoth Lukoil, who has called for an end to the Kremlin’s military assault in Ukraine, announced his departure from the firm he established on Thursday.

Vagit Alekperov’s departure was announced in a brief statement by Lukoil, but no reason was given for his decision to leave Russia’s largest oil producer.

The announcement came less than two months after Lukoil became one of the first major domestic firms to speak out against Russia’s campaign in Ukraine.

“We stand for the immediate cessation of the armed conflict and fully support its resolution through the negotiation process and through diplomatic means,” Lukoil said on March 3.

But Alekperov was still added to a list of sanctions prepared against powerful Russian business leaders by Britain, with which Lukoil has close ties.

Lukoil said Alekperov was resigning as both chief executive and chairman of the company’s board.

The company said he controlled 3.1 percent of Lukoil’s voting shares, and was the beneficiary of another 5.4 percent stake as of March 31.

“Thus, Alekperov is not a controlling shareholder of Lukoil,” the company said.