A former Foreign Office minister has claimed that senior British politicians are being targeted by the Kremlin for potentially compromising details about their private lives that might be used to discredit them.

The Labour MP, Chris Bryant, a former minister for Europe and ex-chair of the all-party parliamentary group for Russia, said he had been a victim of such tactics himself, and was “absolutely certain” that high-profile government figures such as the foreign secretary, Boris Johnson, and the international trade secretary, Liam Fox, will have been investigated by individuals linked to Russia or employed directly by Moscow.

The claim follows the publication of an intelligence file containing unverified allegations that Russian security officials possess compromising material on Donald Trump, including lurid sex videos, that could be used to blackmail the US president-elect. The British author of the controversial material, experienced former MI6 agent Christopher Steele, remained in hiding on Saturday.

In Washington, Trump launched a fresh attack against the documents. The claims, unverified by the media and intelligence services, were gathered by Steele after he was commissioned on behalf of the then presidential candidate’s political opponents.

“Intelligence insiders now claim the Trump dossier is ‘a complete fraud!’ @oann” Trump tweeted in capital letters. The reference to “@oann” was presumably an attribution to One America News Network, a relatively obscure TV channel known for its conservative bias.

Bryant, explaining that incumbent Foreign Office ministers could not speak out on the issue because of security connotations, said: “Any minister who goes into the Foreign Office and has responsibility for Russia, they [Moscow] will be, in any shape or form, trying to put together information about them.

“My main point is that I am absolutely certain that Boris Johnson, Liam Fox, Alan Duncan who has the Russia brief, and [Brexit secretary] David Davis will have been absolutely looked at. All of these people the Russians will be following very, very closely. They will have created a file and they’ll be attempting to watch everything they do.”

Boris Johnson, Liam Fox and other ministers whose brief includes Russia will have been targeted by the Kremlin, according to Bryant. Photograph: Daniel Leal-Olivas/AFP/Getty Images

Bryant, former shadow leader of the Commons until resigning last June, said technological advances made it far easier for enemies to acquire personal information. “You can do a lot of the work by long distance now, you don’t physically have to be close to somebody to be able to track them, using their mobile phones and so on,” he said.

Bryant, an outspoken critic of Vladimir Putin’s record on civil rights, said he had first hand experience of Moscow’s attempts to discredit British politicians. In 2012 he accused the Russian Embassy in London of orchestrating a homophobic campaign against him, a claim it denied.

“When I was chair of the all-party Russia group the embassy helped organise to have me removed. I heard back from various other Conservative MPs who are friends of mine saying that the problem is that Putin hates you and they want rid of you.”

London-based businessman Bill Browder, whose company was one of the biggest foreign investors in Russia before his lawyer Sergei Magnitsky was arrested and died in police custody after exposing a tax fraud worth more than £144m, said he was aware of other former British intelligence agents who had been hired to gather kompromat, compromising material that is intended to be used against someone.

“British companies are being hired to do the work of Russia’s FSB security service. They are collecting sensitive financial and personal information about London-based enemies of the regime as well as spilling the beans on national security and UK foreign policy,” said Browder.

On Friday, the US Senate intelligence committee confirmed it planned to interview senior figures in the incoming Trump administration as part of its investigation into Russia’s alleged attempts to influence the election via hacking and other cyber attacks.

“It is critical to have a full understanding of the scope of Russian intelligence activities impacting the United States,” said the Senate intelligence committee, promising to “follow the intelligence wherever it leads”.

The investigation, backed by Democrats and Republicans, could force testimony from officials both of Barack Obama’s outgoing administration and senior figures in the incoming Trump White House.

It will review the intelligence community’s findings and other assessments, “including any intelligence regarding links between Russia and individuals associated with political campaigns”, the committee said.

But the inquiry falls short of a demand, backed by every House Democrat and many Senate Democrats, for an independent bipartisan commission. Washington has been rocked by intelligence agencies’ conclusion that Russian president Vladimir Putin ordered a covert effort to interfere in the election to boost Trump and harm his opponent, Democrat Hillary Clinton.

But in an interview with the Wall Street Journal, Trump hinted that he might scrap Obama’s retaliatory sanctions against Moscow and said he was prepared to meet Putin after taking office on Friday.

He said he would keep the sanctions in place “at least for a period of time” but then added: “If you get along and if Russia is really helping us, why would anybody have sanctions if somebody’s doing some really great things?”