The British Government gave approval for US investigators to interview a former MI6 agent over his dossier detailing Donald Trump’s alleged ties to Russia, it can be disclosed.

Christopher Steele, who wrote the dossier, was interviewed in London by US officials working with Robert Mueller, the special counsel investigating Russian interference in the US presidential election.

According to well-placed sources, the UK Government gave the greenlight to the officials to travel to London to record Mr Steele’s testimony.

Mr Steele, who ran MI6’s Russia desk and had been a station chief in Moscow, has not travelled to the US since news of the existence dossier became public.

Mr Steele gave detailed testimony for more than 12 hours to two counter-intelligence officers from Mr Mueller’s team in September 2017.