The special counsel overseeing the investigation of Russia’s alleged meddling into the 2016 United States presidential election is probing newly-elected Donald Trump for possible “obstruction of justice”, The Washington Post reported on Thursday. In this regard, counsel Robert S Mueller III has sought interviews with senior US intelligence officials.

US President Trump had received private assurances from sacked Federal Bureau of Investigation Director James Comey that he was not being personally investigated for alleged Russian interference into the US election. However, Mueller III has now sought to question Daniel Coats, the current director of national intelligence, Mike Rogers, head of the National Security Agency, and Rogers’s former deputy, Richard Ledgett. All three men have agreed to the interview next week. Last week, Coats and Rogers declined to answer questions before the US Congress about the matter, reported The New York Times.

Mueller’s office has also asked the National Security Agency for any documents or notes related to the agency’s interactions with the White House as part of the Russian investigation. The NSA said in a statement that it will “fully cooperate with the special counsel” and declined to comment further.

The Washington Post quoted “people familiar with the matter” to say that the investigation into Trump’s alleged obstruction of justice began a few days after Comey was fired on May 9. Comey had confirmed during his congressional testimony on March 20 that the FBI was investigating any possible coordination between Trump and the Russians. Soon after Comey’s testimony, Trump spoke to Coats and Rogers, asking them to intervene in the matter, a request they refused.

As part of the investigation, the special counsel has also collected Comey’s written accounts of his conversations with Trump. The president had accused Comey of lying about these meetings.

Mueller is also overseeing many investigations involving people who are or were in Trump’s orbit. Trump’s possible contacts with Russian operatives as well as any suspicious financial activity is being examined, The Washington Post said.

Comey stated before the US Senate Intelligence Committee last week that he was certain he was fired because of the president’s concerns about the Russia investigation.

Meanwhile, Trump on Thursday lashed out at reports that he is being investigated, labelling it a “witch hunt”.