The Conservative Party has lodged an official complaint to broadcast regulator Ofcom over Channel 4 News’ decision to empty-chair Boris Johnson and replace him with an ice sculpture in an election debate on Thursday night.

The hour-long Emergency On Planet Earth programme was meant to be a chance for each of the party’s leaders to set out their plans to tackle climate change but the PM and the Brexit Party’s Nigel Farage declined to appear.

In a tweet posted before the show, Channel 4 News revealed two ice sculptures would take their place.

In a letter to Ofcom, Tory comms chief Lee Cain lodged an official complaint, stating the Conservative’s offer of allowing Michael Gove to take the PM’s place had been turned down.

The subsequent decision to empty-chair Johnson would “deprive the Conservative Party of any representation and attendance” in the debate, Cain wrote.

The letter then went on to address the ice sculptures:

“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. 

“This would constitute a breach of para7.1 of the Code (“Broadcasters must avoid unjust or unfair treatment of individuals or organisations in programmes”).”

The letter to Tim Suter, chairman of the Ofcom Election Committee, said this “is part of a wider pattern of bias by Channel 4 in recent months”.

Events on Thursday night took another turn for the surreal when it emerged Johnson’s dad had offered to take his son’s place in the debate.

Channel 4 News editor Ben de Pear, tweeted a photo of Stanley Johnson with Michael Gove at the studio where the debate was taking place.

De Pear wrote: “In a last ditch attempt ⁦Boris Johnson has sent his two wing men best friend ⁦Michael Gove and dad Stanley Johnson to argue their way into a programme intended only for leaders. they were lovely and charming but neither are the leader #climatedebate.”

A Conservative source later 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 said.

“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.”

Labour leader Jeremy Corbyn, Liberal Democrat leader Jo Swinson, Scottish First Minister and SNP leader Nicola Sturgeon, Plaid Cymru’s leader Adam Price and Green co-leader Sian Berry agreed to take part.

Asked on Wednesday whether a Conservative minister, such as former environment secretary Michael Gove, could attend the Channel 4 debate instead of Johnson, a spokeswoman for Channel 4 News said: “Michael Gove is not the party leader.”

On Thursday night Gove – who was environment secretary until this summer – posted a video of him talking to Channel 4 staff about whether he could stand in for Johnson.  

“All the other parties will be represented and I just think it’s only fair if we have a Conservative voice there as well,” Gove can be seen saying in the video. 

However, he was not allowed to take part in the debate. Gove said he was rejected by the editor of Channel 4 and the leaders of the other parties taking part. 

“They do not want a Conservative on the platform,” Gove said.

“They wouldn’t accept a Conservative voice. And that means that the ideas we have on the climate emergency, the policies we have to have a cleaner, greener planet won’t be explored tonight.” 

Meanwhile, Tory Party chairman James Cleverly tweeted de Pear: “I just want to check the facts here. 

“We sent someone to represent the Conservatives but you allowed other party leaders to veto their inclusion in the debate? During the regulated general election period?”

But at the end of the programme, Channel 4 News presenter Krishnan Guru-Murthy said the invitation for Johnson and Farage to come and debate the climate emergency “remains open”.

He added: “Thank you to all our party leaders who came tonight. Thank you also to Michael Gove from the Conservative Party who did come here, but sadly, as we made clear from the start, this debate was for leaders only and our leaders were only prepared to debate other leaders.

“Our offer to Boris Johnson and Nigel Farage to come here and discuss the climate emergency remains open.”