The FBI has reportedly frozen the US assets of Russian oligarch Oleg Desipaska in what is seen as a further tightening of the noose around the necks of President Vladimir Putin’s allies.

Mr Deripaska, an industrialist worth an estimated $3.3 billion (£2.5bn) according to Forbes, was placed on a list of individuals sanctioned by the US treasury in April.

Now Washington has frozen Mr Deripaska’s US-based assets, the New York Post reported, including massive mansions in Manhattan and Washington, DC.

The paper claimed that officials are also negotiating with him to give up some of his European-based operations to keep them running free of sanctions.

Mr Deripaska has not entered the US since he was placed under sanctions in the spring, the paper reported.