As it works to investigate Russia's influence on the 2016 American election the head of the House Intelligence Committee abruptly cancelled an open hearing with key intelligence officials on Friday.

There has been "strong pushback from the White House" on the investigation, said the committee's ranking member Republican Adam Schiff (D-AC). The cancellation, he said, clearly "had to do with the events of this week".

During an open hearing with the committee early this week (20 March) FBI Director James Comey revealed that his agency is investigating whether members of the Trump campaign had contacts with Russian officials during the election.

Leaks about several FBI investigations have said communications between Trump campaign officials and associates and Russian intelligence operates have been intercepted.

More was to be learned next Tuesday (28 March) when the committee planned to hear testimony in an open hearing from former Obama administration officials, including CIA director John Brennan, director of National Intelligence James Clapper, and deputy Attorney General Sally Yates.

Late Thursday, however, the committee's chair Devin Nunes moved to hold the hearing in a closed session. After pushback from Democrats on the committee, Nunes instead decided to cancel the hearing on Friday morning.

Nunes (R-CA) defended the cancellation insisting that the hearing was only postponed to hear again from Comey and NSA director Mike Rogers in a closed session. Nunes said that "additional information" from Monday's hearing had come to light and would be brought before him and his peers. The committee, he said, would hear from the other officials at a later time.

Nunes also revealed that President Trump's former campaign chairman Paul Manafort has also volunteered to testify before the committee. On Wednesday the Associated Press revealed that Manafort signed a $10m (£8m) annual contract with Russian aluminium magnate Oleg Deripaska, a close ally of Russian President Vladimir Putin, to influence influence US politics, business and news coverage to "greatly benefit the Putin government."

House Intelligence Committee ranking Democrat Adam Schiff (D-CA) reacts to Committee Chairman Devin Nunes statements about surveillance of U.S. President Trump and his staff as well as his visit to the White House, during a news conference at the US Capitol in Washington, 22 March 2017 Reuters/Jim Bourg

There is no excuse to cancel the hearing, Schiff said, because "these witnesses are available" and have agreed to give testimony. Schiff said that it's important to hold as many of the hearings as the can in public because "there is a lot the public can learn about this and should learn about this."

In the "dead of night" late Tuesday, Schiff said, Nunes had made an excursion in which he viewed intelligence documents "that he hasn't shared with his own committee".

On Wednesday Nunes took the unusual step of holding a press conference to acknowledge that he had seen the intelligence reports and that they showed "there was incidental" surveillance of "the president-elect and his team". Nunes said that all incidental surveillance he had seen was done so legally.

Trump later said that he felt "somewhat" vindicated about claims he had made that President Obama "wiretapped" him and Trump Tower. The claims have been widely dismissed – even by the British government after the White House said their intelligence service carried out the surveillance.

Schiff said that the events of the past week prove that "we really do need an independent commission here" because the American public need to ensure "someone has done a thorough investigation."