A US diplomat has told Congress he overheard Donald Trump on a phone call asking about getting the president of Ukraine to investigate Joe Biden.

Mr Trump was speaking so loudly that the person he was talking to had to hold the phone away from their ear, allowing those nearby to hear what was being said.

The call was described by David Holmes, the political counselor at the US embassy in Kyiv, in evidence given behind closed doors to the impeachment inquiry.

Mr Holmes said he was having lunch with Gordon Sondland, the US ambassador to the European Union, and two others, on the terrace of a restaurant in Kyiv on July 26.

It was the day after Mr Trump had talked by phone to Volodymyr Zelenskiy, the Ukrainian president, pressing him to investigate Mr Biden.

A whistleblower's complaint about that call led to the impeachment inquiry.

During the lunch Mr Sondland used his mobile phone to place the call to Mr Trump.

Mr Holmes said: "Sondland told Trump that Zelenskiy 'loves your ass'.

"I then heard President Trump ask, 'So, he's gonna do the investigation?' Ambassador Sondland replied that 'He's gonna do it,' adding that President Zelenskiy will do 'anything you ask him to.'"