Cameron aims personal attack on PM as polls slip

On Monday, Cabinet Minister Harriet Harman said MPs were subject to the criminal law like anyone else.

"MPs are not above the law, and if they commit an offence, they have to face trial," she told BBC radio.

But she warned Cameron to avoid making any prejudicial statements about the impending prosecutions.

"Because of our doctrine of innocent until proved guilty, it is usual that there is not political comment.

"He's got to be very careful what he says, or his comments might jeopardise the trial."

Labour said on Monday it had suspended the three MPs from the party, "in light of the serious allegations against them."

The Conservatives said on Friday they had suspended Lord Hanningfield. He also resigned as shadow business spokesman in the Lords.

(Editing by Steve Addison)