The left-wing MPs were claiming that the whips were trying to defend the position of Harriet Harman, the health spokeswoman, who is threatened with defeat because of her decision to send her son to a selective grammar school.
One MP said he was approached by a whip and told that if he was away next week, he could leave his ballot form to be handed in by a "reliable" colleague who would cast his votes by proxy.
Alan Simpson, a leader of the left-wing Campaign Group of Labour MPs, said he had heard of MPs being told to leave ballot papers with the whips for proxies to be arranged. "If these allegations are true, it will make a mockery of the democratic process. People are bound to draw conclusions that windfall leave is the reward for windfall loyalty," he said.
"What is happening is a disgrace," another left-wing MP said.
Although proxy voting is within the rules, it could be open to abuse. The rules on proxy voting were tightened up to stop ballot-rigging some years ago after allegations that fistfuls of empty ballot papers were being handed over to whips in exchange for favours such as better rooms and more time off. MPs are now barred from casting multiple proxy votes.
The Commons is due to rise for the summer recess next Wednesday - the day the shadow cabinet results will be announced - and some may relish the prospect of an extra week away from the Commons.
In defence of Ms Harman, it has been made clear to other front-benchers that their posts could be at risk if they break ranks and challenge sitting shadow cabinet members.
The Campaign Group has organised its own "slate" to vote for Irene Adams and Ann Clwyd, two challengers, to remove Ms Harman. They are also backing Margaret Beckett and Ann Taylor, Shadow Leader of the House.
The left-wingers fear she could be at risk for defying Tony Blair and calling on MPs to vote for the 26 per cent pay increase last week.Reuse content