A Conservative Party source appeared to threaten Channel 4 with a review of its licence last night after Boris Johnson was represented by an ice sculpture in a TV climate change debate.

The row comes as the Prime Minister was accused of running scared of this, and other TV appearances, as he refused to confirm he will submit to a grilling from the BBC's Andrew Neil, as other party leaders have done.

Read more: Public's overriding emotion is "frustration" in first TV election debate, says poll

The Conservative's former Downing Street Director of Communications, Lee Cain, has written to complain to Ofcom's election committee after the ice sculpture of the world with "Conservatives" written on it was used in place of Boris Johnson during Channel 4's Emergency On Planet Earth debate on Thursday.

A second ice sculpture replaced Brexit Party leader Nigel Farage, who was also absent.

Labour’s Jeremy Corbyn, the SNP’s Nicola Sturgeon, the Greens’ Sian Berry, LibeDem Jo Swinson and Plaid Cymru’s Adam Price took part.

They debated a range of topics, including the level of ambition for cutting emissions to net zero, how to get to their targets, improving public transport and helping people make their homes more energy efficient. 

Mr Cain said the party had offered the channel former environment secretary Michael Gove to be the party's representative for the debate, but it had insisted the Conservatives would be 'empty chaired' if the Prime Minister did not take part.

"This effectively seeks to deprive the Conservative Party of any representation and attendance at the Channel 4 News debate," the letter said.

"It has even been reported that Channel 4 has commissioned an ice sculpture of the Prime Minister to represent the Conservative Party.

"Were this the case, this would represent a significant breach of the Code through such a provocative partisan stunt, which would itself constitute making a political opinion in its own right."

Claiming this was part of "a wider pattern of bias by Channel 4 in recent months", Mr Cain added:

"I would be grateful if Ofcom could consider this matter with due urgency.

"If Ofcom takes the view that this matter could not be considered until post-broadcast, I would request that this complaint is assessed subsequent to the broadcast, given the unfortunate precedents that Channel 4's actions may set."

Read more: Boris Johnson accused of 'running scared' over TV no-show

It comes as a Conservative source told BuzzFeed News that if the party wins the coming election it will reassess Channel 4's public service broadcasting licence.

"If we are re-elected, we will have to review Channel 4's Public Services Broadcasting obligations," the source told BuzzFeed News.

"Any review would of course look at whether its remit should be better focused so it is serving the public in the best way possible."

Reacting to the reports, Labour shadow treasury minister Clive Lewis said: "Britain deserves a Prime Minister that has enough of a backbone to face up to scrutiny," while Chuka Umunna, of the Liberal Democrats, said: "This is a pathetic attempt to cover up for Boris Johnson's own cowardice."

The row was continued over social media. Conservative Party chair James Cleverly tweeted at Channel 4 News editor Mr De Pear: "This is not a presidential election."

And Mr De Pear said: "Then stop behaving like @realDonaldTrump with the press and media. Put your leader @BorisJohnson alongside the other leaders and stop playing games.

"Don't refuse & then threaten our license it's a slippery slope. All the parties complain about us but they're here #ClimateDebate."

Opponents say Mr Johnson is deliberately avoiding scrutiny as it was disclosed he will miss two other TV debates.

The Prime Minister will not attend the BBC’s seven-way election debate on Friday, and has not yet been pinned down for a half hour interview with Mr Neil, the corporation said.

Mr Johnson is also set to snub the first election leaders’ debate focusing on the climate crisis, which will be broadcast on Channel 4 next Thursday.

The BBC has announced two further one-on-one interviews, in which Jo Swinson and Nigel Farage will take the hot seat alongside Mr Neil, and announced Friday’s debate line-up, with Mr Johnson featuring in neither.

Facing questions on whether Mr Johnson is avoiding the broadcasting veteran, the BBC said they are in “ongoing discussions” with the Prime Minister’s team but “haven’t yet been able to fix a date”.

Ian Lavery, Labour Party chairman, said: “Boris Johnson is running scared.”

A Tory source said: “Discussions are ongoing.”