A Russian deputy prime minister secretly met with oligarch Oleg Deripaska to discuss US relations after Paul Manafort reportedly offered Mr Deripaska briefings on the Trump campaign, according to videos discovered by a Russian opposition activist.

While a recorded snippet of Mr Deripaska's alleged conversation with Sergei Prikhodko, deputy prime minister and head of the government executive office, does not specifically mention Donald Trump, the fact of their meeting on a yacht raises further questions of collusion with Vladimir Putin's government.

The rendezvous at sea with Mr Prikhodko suggests a cosy relationship between Mr Deripaska, the president and largest shareholder of the aluminium giant Rusal, and the Russian government.

It reportedly took place in August 2016, a month after Mr Manafort, then Mr Trump's campaign manager, offered “private briefings” to Mr Deripaska, according to an email seen by The Atlantic.