US Senators investigating Russian interference in the 2016 presidential election are renewing their focus on the activities of Russian oligarchs based in Britain. US congressional investigators say they are particularly interested in interviewing alleged associates of Russian Oligarch Oleg Deripaska, who is known to have close ties with Russian President Vladimir Putin. As part of its ongoing investigation into Russian meddling in the 2016 election campaign, the US Senate Intelligence Committee has now written a formal letter to a London-based security consultant requesting his presence in Washington to give evidence. In the letter, a copy of which has been seen by The Telegraph, the bipartisan committee of US Senators wants British-based security consultant Walter Soriano to attend a special closed session in Washington to answer questions about his alleged association with Mr Deripaska, who has consistently denied any wrongdoing, as well as other key figures named in its Russian investigation. The committee also expressed an interest in Mr Soriano’s possible links with two former MI6 officers, Christopher Steele and Christopher Burrows, who were responsible for producing a highly damaging “dossier” on US President Donald Trump’s alleged ties with Russia. Mr Soriano is an Israeli cyber security consultant whose company USG Security Ltd has offices in London next door to Orbis Business Intelligence, which is run by Mr Steele and Mr Burrows. The committee has asked Mr Soriano to give oral evidence in Washington as well as producing “all documents and records, including hard copies or electronically stored information” relating to any dealings he may have had with a number of key figures in its Russia investigation. These include Mr Deripaska “or any of his employees or associates” as well as “Orbis Business Intelligence, or any of its employees or associates, including but not limited to Christopher Steele and Christopher Burrows”. Senators have also asked Mr Soriano to provide material relating to any dealings he has had with other key figures in their two-year investigation into Russian meddling. These include Paul Manafort, a former key aide of Mr Trump who is serving a seven-year jail term for fraud, Michael Flynn, the Trump administration’s first National Security Advisor, and Victor Boyarkin, a former officer in Russia’s GRU intelligence service who works for one of Mr Deripaska’s network of companies and is now subject to US sanctions. US investigators say the decision to summon Mr Soriano to Washington is a significant step in their attempts to understand the activities of Russian oligarchs linked to Mr Putin in Britain. “We are making progress with the investigation into Russian interference in the 2016 election and we are keen to talk to anyone who may have knowledge of what transpired during that time,” commented a senior US official. Mr Soriano, who is little-known in Britain and is understood to be an Israeli citizen, is a controversial figure in Israel, where he has been accused in the Israeli media of spying on police officers involved in the corruption probe into Israeli prime minister Benjamin Netanyahu, charges he denies. Mr Soriano has also produced a documentary about Mr Netanyahu’s late brother, Yoni Netanyahu, who was killed leading Israel’s raid on Entebbe Airport in Uganda in 1976. The decision by US investigators to refocus their inquiry on the activities of Russian oligarchs and intelligence officers based in Britain follows this week’s warning by Conservative MP Sir Roger Gale in the Commons that Russia was seeking to rebuild its spying network in Britain after most of its spies were expelled in the wake of last year’s Salisbury poisoning. Mr Soriano could not be reached for comment.