The lord chancellor yesterday called for a truce between the Labour party and police investigating the cash-for-honours row.
Lord Falconer warned colleagues they should "stay out of it", after culture secretary Tessa Jowell, Labour peer Lord Puttnam and former home secretary David Blunkett appeared to question the way a key Downing Street aide was arrested.
Their remarks prompted the chairman of the Metropolitan police authority (MPA), Len Duvall, to warn that "no-one in this country is above the law".
On Friday Ruth Turner, Tony Blair's director of government relations, became the fourth person to be arrested by Scotland Yard officers investigating allegations that political parties accepted secret loans in return for seats in the House of Lords.
She was released without charge and denies wrongdoing, but the manner of her arrest - by several officers at in a dawn raid at her London home - has provoked criticism.
Ms Jowell said she was "slightly bewildered" by the circumstances, saying Ms Turner had "fully cooperated and she is a person of utter decency and conscientiousness and I am surprised".
Mr Blunkett said he wanted "thoroughness, not theatre", while Lord Puttnam, a friend of Ms Turner's, said there was "something terribly grotesque" about the events. He added: "Four of them arriving at 6.30 at someone's flat, isn't that a little bit over the top?"
But Mr Duvall warned: "Throughout this investigation the police have, quite properly, refused to comment except to confirm that, as in any other criminal inquiry, they are following where the evidence leads.
"As chair of the MPA I must be seen never to seek to manipulate or pressurise senior officers in the Met on any operational inquiry. Others would do well to follow my example."
The chairman of the Metropolitan Police Federation, Glenn Smyth, also warned politicians must not be seen to be placing "undue pressure" on the police investigation.
"The legacy of this inquiry should be that this was an investigation where the officers without fear or favour followed the evidence trail and did all that was necessary," he said.
"And then when a decision is made by the Crown Prosecution Service we can all have confidence it's done on the basis of all the evidence being available, as opposed to a soft-peddled, punch-pulled, inquiry where the police have been bullied by senior, powerful political people."
Lord Falconer told BBC One's Sunday AM yesterday: "I think we should just stay out of it."