Former UKIP leader Nigel Farage has said he wants to be a "bridge" between the UK and Donald Trump's incoming US administration.
However, speaking to BBC Radio 4's Broadcasting House programme, Mr Farage claimed cabinet ministers had been banned from talking to him.
But senior Tory MP Crispin Blunt said he was being a "political gadfly" and had not taken advice from diplomats.
Number 10 has rejected Mr Farage's offer, saying "there is no vacancy".
The UKIP MEP was the first British politician to meet Mr Trump after his US presidential election victory in November.
He has since held two further meetings with the president-elect, who has said Mr Farage would make a good UK ambassador.
Mr Farage told the programme he did not expect to get a role in the new US administration because of his British passport.
But he said the unwillingness of the UK government to use him as an intermediary with Mr Trump showed how "petty, small-minded and tribal" British politics was.
Mr Blunt, chairman of the Commons foreign affairs committee, told BBC Radio 5 Live's Sunday Breakfast programme that if Mr Farage was serious, he would get in touch with British diplomats to be briefed instead of "striking a pose" for television.
"I know for a fact he's not sought advice from the British Embassy in the United States and put his connections at the disposal of the British government," he said.
"All he's done is communicated this through the media."
International Trade Secretary Liam Fox also denied Mr Farage's claim that the cabinet had been banned from talking to him.
"I've not had any such instruction," he told the BBC's Andrew Marr Show..
Mr Farage told the BBC Britain's "political revolution" was incomplete - and there would ultimately be a similar upheaval to Mr Trump's takeover of the Republican Party.
He said he was "hacked off" by the term "populist" being to describe anyone opposed to what he called the "global elite", saying it was a deliberately pejorative term.
Asked about the rise in hate crime since the referendum, the former UKIP leader said he had endured four years of "endless" death threats - and that it was not just one side of the referendum argument who had behaved badly.
He said he had received 10 death threats in the past two weeks alone.
Paul Nuttall was elected leader of the UK Independence Party in November, replacing Mr Farage who was acting interim leader after Diane James quit just 18 days into the role.
Broadcasting House can be heard on BBC Radio 4 at 09:00 GMT on Sundays