Donald Trump used to tape conversations and meetings in his Trump Tower offices prior to becoming President, according to three unnamed high-ranking former employees.

The claim comes after the President appeared to threaten the sacked FBI chief James Comey, tweeting that he "better hope there are no 'tapes' of our conversations before he starts leaking to the press”.

At a press briefing on Friday, press secretary Sean Spicer repeatedly refused to say whether Mr Trump was secretly recording meetings with visitors.

Mr Spicer would only say “the President has nothing further to add on that. The tweet speaks for itself.”

However, three high-ranking former employees have now told the Wall Street Journal that Mr Trump had one or more recording devices that he used to tape phone calls from his office.

There is no federal law governing the recording of conversations, and surveillance rules varies by state.

Taping conversations is legal in New York, where Trump Tower is, and in Washington DC, so long as one of the participants is aware that it is being filmed.

Some former associates of Mr Trump have said they can prove he recorded phone calls, because tapes of their conversations with him were submitted as evidence in court cases.

In 1989, Pratt Hotel Group sued claiming Trump Holdings had illegally interfered with attempts to buy a construction site next to the Trump Plaza casino.

Trump says Comey was fired for 'not doing a good job'

During the lawsuit, the President’s legal team produced a recording of a conversation between Pratt’s president and Mr Trump, contradicting Pratt’s version of events.

Democrat Senators have demanded that any tapes of conversations concerning the contentious firing of FBI director Mr Comey, who was investigating Mr Trump’s ties to Russia, must be made public.

Adam Schiff, the senior Democrat on the House intelligence committee, said on Twitter: “Mr President, if there are ‘tapes’ relevant to the Comey firing, it’s because you made them and they should be provided to Congress.”

Many commentators have explicitly compared the firing to the Watergate scandal, in which the Republican administration wire-tapped the offices of Democratic National Committee headquarters.