LONDON — ITV's televised general election leadership debate will go ahead without either Theresa May or Jeremy Corbyn, after both the Conservative and Labour leaders ruled out taking part.

ITV on Wednesday announced that they have invited all the major party leaders to stage a debate on May 18th.

However, the prime minister has already ruled out taking part in any debate with other party leaders, insisting that she had already debated them in Parliament.

A spokesperson for Labour leader Jeremy Corbyn today also ruled out taking part in any debate without the PM also agreeing to join him.

"Jeremy will not take part in an opposition leaders debate," a spokesperson told Business Insider.

"The British people have the right see a head-to-head debate between the only two people who could form the next government - and the Prime Minister's refusal is a sign of weakness, not of strength."

A spokesperson for Corbyn explained to BI last week that they were not willing to "empty chair" the PM.

"I don't think that having a debate among opposition parties in any way meets the objective of giving the British people a chance to see what the real choices are in this election campaign," they told BI.

"Our challenge is to the Prime Minister to have the strength and guts to actually face a direct debate with Jeremy Corbyn on the issues facing the country, " he said.

He added that: "If you're talking about a debate about the possible outcomes of the general election then you're talking about a debate between the Conservative party and the Labour party."

An ITV spokesperson said that their debate would still go ahead.

"ITV will again broadcast a major debate programme in 2017, inviting the leaders of the seven parties that were represented in the 2015 ITV Leaders' Debate — the Conservatives, Labour, SNP, Liberal Democrats, UKIP, Plaid Cymru and the Greens," they said.

"The ITV Leaders' Debate will air on Thursday May 18th at 8pm, and will be moderated by ITV News anchor Julie Etchingham. As in the previous two General Election debates, leaders will have the opportunity to make short opening statements at the beginning of the programme and closing statements at the conclusion of the debate. During the live debate, the leaders will have the opportunity to each in turn answer questions that are asked direct by members of the studio audience, before the floor is opened up to a period of free flowing debate."

The BBC have yet to spell out their plans. However, party sources have told BI that the prime minister is likely to agree to a Question Time style session on the channel.

A report in Politico today suggests that the BBC are reluctant to empty-chair the PM and are therefore considering allowing party leaders to send substitutes to represent them at the debate.

"The BBC have chickened out so as not to upset Downing Street," one source told the site.

Liberal Democrat leader Tim Farron on Wednesday challenged his rival party leaders to join him in the debates.

"Tim will be taking part in the debate and is looking forward to the opportunity to make the Liberal Democrat case. We believe this election is an opportunity to change the direction of our county," he said.

"We expect our hard-Brexit opponents – Labour, UKIP and the Prime Minister, Theresa May to all take part and make their opposing case. Otherwise, we expect ITV to empty chairs them.

"Tim believes, in politics, you must have the courage of your convictions. Let’s see if May and Corbyn feel the same."