Jeremy Paxman is one of the BBC's best known faces

The Tory leader is understood to be furious about the way a visit to Cornwall was covered by the programme.

Mr Howard's press secretary Guy Black said the report was "partisan" and biased and no effort had been made to balance negative comments it contained.

The report, broadcast on Monday, triggered a large viewer response.

'Robust'

That prompted Newsnight editor Peter Barron to defend Mr Paxman's "robust" approach in an article on the BBC's NewsWatch website.

"Jeremy's interviewing style is famously robust - but it is robust whether he is interviewing politicians from right, left or centre," Mr Barron wrote.

Mr Howard has complained to the BBC

He added: "The piece had been negotiated with the Conservative Party over many months.

"We hoped to have unfettered access to Mr Howard during his trip to Cornwall but, as it turned out, once on the ground our access was very limited.

"Jeremy therefore interviewed the people he found and simply asked them what they thought of current Conservative fortunes - these included the farmer in whose field Mr Howard's helicopter was to land, the Tory activists who turned out to meet him, and members of the public in Falmouth."

The Conservatives feel there was no attempt to balance negative comments from members of the public with more favourable ones.

They are also thought to be upset about a short face-to-face interview with Mr Howard, in which Mr Paxman asked him about former prisons chief Derek Lewis - the subject of a former confrontation between the two, eight years ago.

A spokesman for the BBC confirmed a complaint had been received from the Conservative Party and it was being considered.