WASHINGTON, September 28. /TASS/. United States Special Representative for Ukraine Kurt Volker tendered his resignation a day after the release of a report by an anonymous whistleblower regarding the conversation between the presidents of US and Ukraine, CNN reported on Friday citing three sources familiar with the situation.

"Kurt Volker, US special envoy to Ukraine, has resigned one day after the release of a whistleblower report alleging a coverup by the White House of a call between President Donald Trump and Ukraine's President," the TV channel reported.

A TASS request to the US Department of State to officially confirm the information has been left unanswered at the time of the publication.

Earlier on Friday, the Democratic minority in the US congress summoned Volker to testify about the contacts between Trump and Ukrainian President Vladimir Zelensky, supposed to take place on October 3.

According to the whistleblower complaint, published on Thursday by the House Intelligence Committee, Volker ad US Ambassador to EU Gordon Sondland met with Zelensky after his June conversation with Trump to provide him and other state officials with directives on the investigation regarding Ukrainian gas company Burisma, linked to the son of former US vice president Joseph Biden.

The allegations Trump had exerted pressure on Zelensky to persuade Kiev to indirectly help him secure re-election for a second term in 2020 triggered a row in Washington. Trump’s opponents claimed that the US leader sought to exert pressure on Ukrainian President Vladimir Zelensky to launch an investigation of Hunter Biden, whose father, former US Vice President Josef Biden, is now Trump’s most probable rival at the upcoming presidential elections. The Democratic Party-controlled House of Representatives on Tuesday used the suspicion to launch impeachment procedures against Trump. Biden is currently regarded as one of Trump’s most likely rivals in the presidential election due next year.

The White House on Wednesday released a transcript of last July’s conversation between the two leaders. It turned out that Trump by no means urged Zelensky to order an investigation of Hunter Biden in exchange for Washington’s financial and military assistance to Kiev. The US Department of Justice has found that last July’s Trump-Zelensky conversation contained nothing that might constitute a violation of the national legislation or any reasons for further investigation or other action.