The EU of the future will need a "streamlined" decision making process, Tony Blair told the Commons on Monday.

As an enlarged union grows from 15 to 25, or more, member states "it is obvious that the EU cannot work in the same way, with precisely the same constitution", the prime minister said to MPs.

"Decision-making will need to be streamlined. EU laws will need increasingly to take the form of framework legislation, with the details of implementation left to member states," he said.

Blair also announced that a European constitutional convention on the future of the EU would be "looking again at the size and role of the commission, reviewing the workings of the existing presidency of the union, and managing the business of the various specialist councils in amore coherent way".

In a restatement of his government's position on the question of sovereignty, the PM welcomed the EU's contribution to delivering "peace, stability and prosperity" for Europe. "The British view, widely shared, is that while it is right to cooperate ever more closely with our partners, democratic accountability is fundamentally and ultimately rooted in the member state."

Dismissing Conservative fears of a euro super-state, Blair said that last weekend's Laeken declaration and convention would mean "looking at the prospect of restoring some tasks to the member states". "We also have the chance of opening up the European institutions to greater public scrutiny. And the role which I want to see our parliament playing in policing that process is now explicitly recognised," he said.