JEREMY Hunt has strongly criticised the BBC for offering to stage a head-to-head TV debate with his Tory leadership rival Boris Johnson – after most party members will have cast their votes.

The Foreign Secretary said he had been invited to take part in a debate on July 16, by which time, he said, around 90% of the party membership would have cast their votes.

"Absolute joke to give the appearance of a debate whilst knowing it can have ZERO influence on campaign. Also very disrespectful to members and the public," he tweeted.

Hunt went on to accuse the corporation of "caving in" to pressure from Johnson's spin doctor, Sir Lynton Crosby.

"Other broadcasters had the courage to empty-chair no-shows. What happened to scrutiny without fear or favour at the BBC?" he said.

"Beeb journalists will be deeply uncomfortable at this caving to Lynton Crosby. Come on BBC – this is for OUR PRIME MINISTER!"

Hunt has persistently accused his rival of ducking head-to-head confrontations during the course of the campaign, including refusing to take part in a proposed showdown on Sky News.

Johnson has so far agreed to take part in only one debate between them –on ITV on July 9.

There is concern within the Hunt camp, however, that, by the time it takes place, the postal voting papers will already have gone out and many members will have voted, limiting its impact on the outcome of the campaign.

They fear that the proposed BBC debate a week later – just a week before the final result is announced – will have even less effect.

The BBC said in response that it was keen to host a Question Time special debate with the two candidates and had been trying to agree a date.

"Both candidates have already taken part in the first BBC debate, both have been interviewed by our political editor, and both have agreed in principle to participate in a Question Time special," a spokesman said.

"We don't think it's reasonable to empty chair people who have already participated in interviews and debates and have agreed to take part again.

"Clearly any date needs to fit in with the candidates' existing commitments such as hustings and other TV appearances. July 16 is before the last Conservative hustings and the voting will still be open.

"But, crucially, our debate is about the next prime minister and we think it's important both candidates speak to the whole of the UK, as well as the members of the Conservative Party."

The spokesman said they had also invited both candidates to be interviewed consecutively by Andrew Neil for a BBC One special."