(CNN) Boris Johnson was criticized by party leaders and represented by a dripping ice sculpture after refusing to appear in a televised election debate focusing on climate change, sparking a row between the UK broadcaster and the Prime Minister's Conservative Party.

The Conservatives complained to the UK's broadcasting watchdog Ofcom ahead of the Channel 4 event, which saw Labour leader Jeremy Corbyn, Liberal Democrat Jo Swinson and the heads of the UK's other main parties quizzed on their plans to tackle the climate crisis ahead of next month's poll.

The party said its offer of having minister Michael Gove stand in for Johnson was rejected by Channel 4, complaining the decision "effectively seeks to deprive the Conservative Party of any representation and attendance at the Channel 4 News debate."

The network said the event was only for party leaders, and opposition leaders have lambasted Johnson for dodging scrutiny by refusing to appear.

An ice sculpture is put in place for Prime Minister Boris Johnson at the debate.

The event took place on the day that scientists warned the earth is heading to a "tipping point," and hours after the European Parliament voted to declare a climate emergency. The UK became the first country to make such a declaration in May, after Corbyn's Labour Party led a successful push to do so. Corbyn earlier announced a plan to plant 2 billion new trees by 2040.

Before the debate started, the program's editor had earlier said Johnson "sent his two wing men" -- Gove and Johnson's father, Stanley -- to attempt to "argue their way into" a program intended only for leaders. Stanley Johnson was there to conduct interviews in the so-called spin room after the debate, he later clarified.

Johnson and fellow no-show Nigel Farage, the leader of the Brexit Party, were ultimately replaced at the debate with ice sculptures bearing their parties' logos, which Channel 4 said was intended to "represent the emergency on planet earth."

Johnson's refusal to appear in the debate gave further fuel to charges that he is avoiding media appearances during the campaign. Several opposition figures have also criticized him for refusing to confirm he would take part in an interview with BBC presenter Andrew Neil, which all of the other major leaders have done.

"The reason he is doing it is because he thinks, like you know his Bullingdon Club friends, that they're above the rest of us," Labour's shadow Chancellor John McDonnell told the BBC on Friday, referring to a controversial Oxford University club of which Johnson was a member. "And so what he's doing now is he's avoiding, he's running scared."

Farage, meanwhile, said he refused to take part because "Brexit is the defining issue of our age and the fact that Channel 4 does not want to discuss it speaks volumes about this broadcaster and its Remain position."

A similar refusal by Johnson's predecessor Theresa May to take part in a TV debate during the 2017 election backfired on the then Prime Minister, who ultimately lost seats in the election.

Johnson is currently enjoying a healthy majority in opinion polls, but Labour have closed the gap in recent days.