Three Russian billionaires have resigned from the board of a $22 billion investment firm amid their country’s ongoing invasion of Ukraine.

It comes after London-based LetterOne froze out Mikhail Fridman and Petr Aven, who are subject to Western sanctions, blocking access to their buildings last week and forbidding them to talk to employees.

LetterOne is set to donate $150 million to help people affected by the war in Ukraine, and shareholders have agreed that all dividends will go toward relief efforts, a company statement said.