DAVID Cameron is “not being straight with the British people” over the cost and complexity of constitutional reform, Ed Balls said.
The shadow chancellor accused the Prime Minister of talking “complete nonsense” over his demands that Scottish MPs be quickly stripped of the right to vote on laws affecting only England.
And he said rushed reforms risked “undermining the Union we have all just fought to save”.
Mr Cameron’s move to link the change to the cross-party timetable agreed for new powers for Holyrood in the wake of Scotland’s rejection of independence in last week’s referendum has angered Labour and dominated the start of its annual conference in Manchester.
The Prime Minister announced within hours of the No vote that the process for looking at the so-called “West Lothian question” would proceed at the same pace as the settlement for Scotland - putting pressure on Labour to agree to the move.
Opposition leader Ed Miliband has backed greater “scrutiny” of England-only legislation by English MPs but stopped short of a pledge on votes, arguing that a major constitutional change should not be drawn up in a rushed “back of the envelope” way.
He is calling instead for a Constitutional Convention to be held - based on a consultation across the UK.
Labour, which has 40 of Scotland’s 59 MPs, has most to lose from any measures which would restrict the voting rights of MPs representing constituencies north of the border.
Mr Cameron is gathering senior MPs at his official country retreat today to consider his proposals, with some senior figures in his party urging him to go further and introduce a separate English parliament.
Mr Balls told ITV’s Good Morning Britain: “Are we really going to start dividing our Parliament in this way?
“I don’t think it’s the best way at all to deliver the fairness we need to see. I want more devolution in England, I want a fair deal for my constituents.
“We should start by listening to people, rather than William Hague deciding it in a Cabinet committee.
“But David Cameron, giving the impression that he can do it in a couple of months, I think he is not being straight with the British people and we are not going to play those kinds of games.
“There is no easy solution to that and we are not just going to come along with something which is half-baked. It can’t be decided by Conservative Cabinet ministers.”
He went on: “That is a complete nonsense from a Prime Minister, David Cameron, who is desperately trying to hold his fractured party together.
“It is a rubbish thing to say.
“We can go ahead and we can put in place the changes for Scotland on a timetable we have agreed and we can make sure then, at the same time but over the next two years, we consult properly to make big changes to our constitution for the future.
“David Cameron’s proposal could end up with him saying he wants two parliaments, or he wants to have two different prime ministers. That would cost huge amounts of money, be incredibly expensive.
“That’s why, when people have looked at these things over the past decades, they have concluded that what for David Cameron looks glib and easy actually is not very easy when you look at the detail.”
Mr Balls told Sky News: “We need, after Scotland, to make sure we have constitutional change which is fair to the regions and people of England, to my constituents as well as to Wales and to Scotland.
“But you don’t do that on some rushed timetable decided by politicians.
“You go out and talk in the country...and find a way forward which doesn’t end up costing more in the cost of government or having two parliaments or two prime ministers, or undermining the Union we have all just fought to save.
“We can have fairness and keep our Union. David Cameron giving the impression somehow this is dead easy, he is just trying to fool people and he won’t get away with it.”