A White Paper setting out the Government's detailed plans for the Welsh Assembly and the Scottish Parliament will be published "well ahead" of the referendums, Donald Dewar, the Secretary of State for Scotland, told the Commons.
Ministers will use the referendum results to limit the challenges to the main legislation by Tories, anti-devolution Labour MPs including Tam Dalyell, and the House of Lords.
The Tories are expected to table amendments for thresholds to be achieved in the referendum, in the Bill's committee stage, which will be taken on the floor of the House after the Whitsun recess.
Mr Dewar warned the Tories they would be accused of "ballot rigging" if they tried to "revisit" the 40 per cent rule - requiring a yes vote from at least 40 per cent of all eligible voters, on which the 1979 Labour referendums foundered.
Michael Howard led Tory protests that the people of Wales and Scotland would be asked to vote in the referendums on the principle of devolution before the main legislation to establish the Welsh Assembly and the Scottish Parliament has been introduced in Parliament. And Mr Howard warned that the Union would "begin to fray in a matter of months".
The chasm between the two front benches over the passage of the Referendums (Scotland and Wales) Bill threatens to continue through the summer as the Tories, under a new leader, are expected to campaign for a "No" vote.
However, the Tories came under immediate fire from the Liberal Democrats for being allowed to open the debate for the Opposition, when they had failed to win any seats in Scotland and Wales in the election.
Rejecting the claims that the Tories lacked legitimacy to oppose devolution, Mr Howard, the former home secretary, said Labour feared the public would turn against devolution, if they knew the details before the referendums were held.
"That is why the Government is resorting to this unprecedented and anti- democratic approach," Mr Howard said. There were also Tory backbench protests, led by Bill Cash, a leading Euro-sceptic, over the refusal to allow English voters a referendum. But Labour MPs shouted: "They have had a vote - and you lost mate!"
Mr Dewar said there was genuinely a mood for change in Britain. He promised the substantive legislation would be introduced before the end of the year, and elections to the new Scottish Parliament would be held as "soon as practical after Royal Assent - I believe we can have a parliament in place to welcome the millennium."Reuse content