Donald Trump is facing a problem at a time when he is in New York to attend the UN General Assembly.

US President Donald Trump was subjected to an embarrassment when the MSNBC news channel cut away from his press conference while he was speaking on the controversy surrounding him over the Ukrainian probe against former Vice President Joe Biden.

Trump on Wednesday was addressing the press conference against the backdrop of impeachment proceedings announced against him by House Speaker Nancy Pelosi following allegations that he put pressure on the Ukrainian President Volodymyr Zelensky to order a probe against Biden whose family has business interests there.

The allegation against Trump came to light because of a whistleblower and a transcript of the conversation between him and Zelensky in July, which has become public.

As Trump was speaking to the media after meeting Zelensky to clarify his position, MSNBC host Nicolle Wallace cut into it, saying: "We hate to do this but the President isn't telling the truth."

She added that Trump was trying to do it to deflect the attention from his impeachment.

According to the transcript of the telephonic conversation that has gone public, Trump is heard asking Zelensky to "do us a favour", after the latter expresses gratitude for the military aid the US provided to his country.

Trump's words of "do us a favour" is seen as a quid pro quo for the American military aid, because of which the impeachment proceedings have been announced.

After Wallace cut the press conference, her guest on the programme, justice and security analyst Matthew Miller, rebuked Trump for saying that Biden and his son had done wrong.

"This story has been looked at and thoroughly debunked by everyone involved," Matthew Miller said, adding the real issue was whether Trump's conduct is "impeachable".

Donald Trump is facing a problem at a time when he is in New York to attend the UN General Assembly.