(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.

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