US President-elect Donald Trump in the lobby at Trump Tower in New York on Monday. REUTERS/Mike Segar LONDON — Sir Andrew Wood, a former British ambassador to Moscow, played a key role in alerting US intelligence services to the unverified claims that emerged this week of links between US President-elect Donald Trump and Russia.

Wood told US Sen. John McCain last year that Trump's potential Russian connections demanded closer inspection, according to multiple reports on Friday. The exchange is said to have taken place at an international security conference in Canada in November.

The Independent reported that McCain asked Wood specifically about the dossier compiled by former British intelligence officer Christopher Steele that BuzzFeed published on Tuesday. Following the conversation, McCain passed the dossier of lurid claims to the head of the FBI, the reports said.

Wood's involvement goes some way to explaining why the dossier was taken so seriously by security officials in the US and why they felt the need to brief both Trump and US President Barack Obama. The document came from a senior MI6 agent, and Wood took it seriously. US Sen. Harry Reid, who retired at the beginning of this year, had also been briefed on the document and, like McCain, demanded an investigation of its claims by the FBI. The FBI also reportedly took out a FISA warrant to investigate the document, according to Heat Street.

Trump has denied the dossier's claims as "fake news" and called out Steele as a "failed spy afraid of being sued" on Tuesday.

More support for Trump dossier author

Wood, who served as the British ambassador to Russia from 1995 to 2000, told the BBC that he knew Steele and trusted his work. "I know him as a very competent professional operator who left the secret service and is now operating his own private company," he told Radio 4's "Today" programme on Friday.

His support for Steele follows a report in The Guardian in which sources close the former British spy vouched for his experience and expertise. Steele was the former head of MI6's Russia desk, the report said, and has maintained a network of sources in the country.

Christopher Steele. BBC Furthermore, former MI6 officer Harry Ferguson praised Steele on the BBC show "Newsnight" on Thursday. "It seems to me that Chris was careful, as to try and find as many sources as possible to back these stories up, but also to make it clear that these are stories, and that what this intelligence report has at the moment is that it lacks that killer evidence," he said.

Steele has reportedly gone into hiding after the Trump dossier was leaked, fleeing his home on Wednesday. A source close to Steele told The Daily Telegraph that he was worried about a dangerous backlash against him from Moscow.

His 35-page report described Trump as engaging in compromising activities in Russia and coordinating with Kremlin officials during his presidential campaign. Steele's findings, which have not been confirmed but which attracted the interest of US intelligence officials, were apparently based on conversations he had with Russian intelligence sources. His work was financed by anti-Trump Republicans and later Democrats during the US presidential campaign.