Gordon Brown was today urged by Speaker Michael Martin to use " temperate language" as the row over the Scottish elections debacle flared again in the Commons.
Mr Martin made his appeal after the Prime Minister accused Tory leader David Cameron of "misleading" people by suggesting that a critical report published yesterday into the fiasco only blamed one party.
Mr Brown said all the parties must share the responsibility because they all agreed the system adopted for the May 3 poll in which 140,000 ballots rejected.
Mr Cameron hit back that he did not know how the PM had the "gall" to accuse him of misleading anyone.
And he called for former Scottish Secretary Douglas Alexander to explain himself to MPs and be stripped of his current responsibility for elections.
Earlier outside the House, former Scottish Secretary Douglas Alexander apologised for his role in the fiasco.
Mr Alexander, now International Development minister, had faced calls to resign after international expert Ron Gould's report claimed that Scottish ministers - in Edinburgh and London - focused on partisan political interests and voters were treated as an "afterthought".
The report found that "almost without exception, the voter was treated as an afterthought".
A key factor in voters' confusion was caused by having both Scottish Parliament ballots on one voting sheet, and these should be on separate papers in future, it found.
Raising the report at question time, Mr Cameron said: "It found that the Labour Government put party interest before voters' interest in conducting those elections.
"Will you now offer your own personal apology for the unacceptable conduct of ministers?"
But Mr Brown hit back: "I don't accept that at all.
"What the Gould report said was that there were decisions made about the elections that could have been better made," he added to loud Tory jeers.
"These decisions were supported by the Conservative Party," Mr Brown persisted.
"What the Gould report does not do is put the blame on any individual or any institution.
"What it says is that all political parties must take their share of responsibility for what happened."
Mr Cameron taunted: "I thought politics was going to be different under you."
The conclusion that ministers focused on partisan political interest was "a complete scandal", he added.
As the Commons grew increasingly rowdy, Mr Martin intervened several times to appeal for order and warn MPs to be quiet.
Referring to Mr Alexander, the Tory leader demanded: "How can he possibly go round the world lecturing other countries about probity in their elections?"
Mr Brown hit back: "Because you are misleading people about the conclusions of this report."
As furious Tories demanded the PM withdraw the allegation, Mr Martin, after consulting with his clerks, told the House: "I call for temperate language."
Mr Brown said the report did not assign blame to any one party or institution.
"What he (Ron Gould) is saying is the political system must change and that is why we have accepted his recommendation."
Mr Cameron angrily replied: "I don't know how you have the gall to accuse me of misleading anybody.
"You should have a look at page 17 of the report that says there was a notable level of party self-interest evident in ministerial decision-making."
And he added: "Isn't the least we deserve that the minister who took these decisions explains himself to the House of Commons and is stripped of his responsibility for elections?"
Mr Cameron concluded: "You promised us a new type of politics. You said you would be more open and honest. You said you would be frank about problems.
"You said you would be candid about the dilemmas.
"That was in your leadership speech 100 days ago. After your performance today doesn't that feel like 100 years ago?" he demanded, to deafening shouts of agreement from Tories.Reuse content