The contents of the whistleblower’s complaint about Donald Trump’s call to the leader of Ukraine are “deeply disturbing”, according to politicians who read the material.

Senior members of the Senate and the House of Representatives received copies of the document filed by a member of the US intelligence community, whose concern about the president’s July conversation sparked the crisis facing the president.

Mr Trump claimed the whistleblower, whose identity has not been made public, did not “have any first class or first rate or second tier information”.

However, politicians who examined the complaint suggested they too were troubled.

Republican Ben Sasse, a member of the Senate intelligence committee, told reporters there were “real troubling things” in the materials.

Everyone Trump has fired or forced out Show all 13 1 /13 Everyone Trump has fired or forced out Everyone Trump has fired or forced out John Bolton Trump claimed to have fired Bolton, his national security adviser, while Bolton claimed he offered to resign. An anonymous White House source that Bolton's departure came as a result of the national security adviser working too independently of the president AFP/Getty Everyone Trump has fired or forced out Anthony Scaramucci Scaramucci lasted only six days in his role as Trump's communications director before being fired by John Kelly, the incoming chief of staff Getty Everyone Trump has fired or forced out Rick Perry Rick Perry announced his resignation just as he became embroiled in the president's impeachment scandal. The White House said Mr Perry was asked by Donald Trump to work with Rudy GIuliani in regards to Ukraine. AP Everyone Trump has fired or forced out Rex Tillerson Tillerson, Trump's first secretary of state, was fired after a series of clashes with the president over policy Getty Everyone Trump has fired or forced out James Mattis Mattis served as secretary of defense from the beginning of Trump's administration until retiring on 1 January 2019. However, the president later claimed that he had "essentially fired" Mattis Getty Everyone Trump has fired or forced out James Comey Comey was fired as director of the FBI early in Trump's presidency after serving in the role for four years prior. His dismissal is widely thought to have been related to the Russia investigation Getty Everyone Trump has fired or forced out Reince Priebus Priebus, Trump's first chief of staff, was forced out after six tumultuous months AFP/Getty Everyone Trump has fired or forced out David Shulkin Veterans affairs secretary Shulkin claims that he was fired, the White House claims that he resigned Getty Everyone Trump has fired or forced out John Kelly Kelly, Trump's second chief of staff, was forced out after 17 months in office. His departure was a confused affair though it is clear that Trump wanted Kelly out AFP/Getty Everyone Trump has fired or forced out Michael Flynn Flynn lasted 24 days as Trump's national security adviser before being fired for lying to the FBI Getty Everyone Trump has fired or forced out Lee Cisna Cisna served as director of citizen and immigration services between October 2017 and June 2019 before being asked to resign amid a major personnel change in the department of homeland security Everyone Trump has fired or forced out Madeline Westerhout Westerhout served as Trump's personal assistant after leaking private information about his family AFP/Getty Everyone Trump has fired or forced out Mira Ricardel Ricardel was forced out of her role as Deputy National Security Advisor after first lady Melania Trump publicly called for her to be fired

“We need to slow down. This place is terrible at deliberation. Democrats ought not to be using the word impeach before they had the whistleblower complaint or read any of the transcript,” he said.

“Republicans ought not to be rushing to circle the wagons and say there’s nothing there when there’s obviously a lot that’s very troubling there.”

Senate Democratic leader Chuck Schumer said the document was “very troubling”.

He added: “There are so many facts that have to be examined."

Trump uses UN setting to attack critics in rambling speech: 'How can they impeach for that?'

House intelligence committee chairman Adam Schiff said after reading the document he found the whistleblower’s allegations “deeply disturbing” and “very credible”.

The intelligence committees of both chambers reviewed the complaint after it had been withheld for several weeks because acting Director of National Intelligence Joseph Maguire, had determined it wasn’t an “urgent concern”.

He will appear on Capitol Hill where he will be questioned by members of Congress.

Another Democrat who read the material, senator Mike Quigley of Illinois, told CNN he also found it “deeply disturbing”.

He said the complaint was “extraordinarily detailed and very, very well done”. He added: “It reinforces the concerns that what we previously learned and I think it is a blueprint for what we still need to know. It lays out exactly what Congress needs to investigate.”

Earlier this week Democrats announced they were launching formal impeachment proceedings against Mr Trump after it emerged he had asked Ukraine president Volodymyr Zelensky, to investigate political rival Joe Biden and his son.

The president has denied doing anything wrong.