Former energy minister Greg Barker will step down as chairman of a Russian aluminium giant and auditors PwC and KPMG are cutting ties with the country as businesses react to sanctions against Moscow.

Lord Barker, who served in David Cameron’s government, announced his resignation from the board of EN+ on Monday.

He has held the position of chairman since 2017, and was made executive chairman in 2019.

He will step down after a transition and hand over to New York-born Christopher Bancroft Burnham, a former under secretary general at the United Nations.

The announcement came after auditing giants PwC and KPMG said on Sunday they were cutting ties with their Russian businesses.

PwC, which employs 3,700 people in the country, said: “As a result of the Russian government’s invasion of Ukraine we have decided that, under the circumstances, PwC should not have a member firm in Russia and consequently PwC Russia will leave the network.”

KPMG employs 4,500 people in Russia and Belarus, which has been accused of aiding the Kremlin in its attack on Ukraine.

It said: “We believe we have a responsibility, along with other global businesses, to respond to the Russian government’s ongoing military attack on Ukraine.

“As a result, our Russia and Belarus firms will leave the KPMG network.”

Separately, London-headquartered law firm Norton Rose Fulbright said that it would also wind down its operations in Russia.

“Norton Rose Fulbright stands unequivocally with the people of Ukraine who are suffering as a result of the increasingly brutal invasion by Russia,” it said.

The business said it would support its 50 staff in the country during the transition.

It added: “Some immediate actions are possible and we are taking them. We are not accepting any further instructions from businesses, entities or individuals connected with the current Russian regime, irrespective of whether they are sanctioned or not.

“In addition, we continue to review exiting from existing work for them where our professional obligations as lawyers allow. Where we cannot exit from current matters, we will donate the profits from that work to appropriate humanitarian and charitable causes.”