The outcome of the Nice summit represents an advance for Britain and an advance for Europe, the prime minister told the House of Commons on Monday.

In a statement to MPs Tony Blair said the treaty agreed at Nice will pave the way for an enlarged EU whilst ensuring Britain's national interest in key areas was maintained. It represented, Blair said, Britain "getting the best out of Europe". William Hague, however, said that the Nice treaty would actually make it more difficult for new countries to join the EU.

Blair said the marathon summit, which nearly fell apart in the small hours of Monday morning, paved the way for expansion of the European Union.

He defended the government's decision to back the extension of qualified majority voting into areas such as the appointment of the president of the European commission. He said Britain would stand to benefit from the extension of QMV into areas such as financial services, industrial policy, the procedures of the Court of Justice and regulations affecting the EU's budget.

Blair also defended the European rapid reaction force stressing the elements of the treaty which re-iterated that it will only act where NATO has decided not to do so and that individual member states remain sovereign when deciding whether to commit troops.

The prime minister also claimed that the British had won key concessions - most notably on the issue of re-weighting to ensure that the big nations of the EU remain the most powerful in the EU decision-making process. Robin Cook said that for the first time Britain could look forward to enlargement without seeing a reduction in its voting power.

Blair also claimed victory on Britain's budget contributions saying that "by 2006 net contributions will be equal to France and Italy for the first time". He also mocked William Hague's stance on Europe, stressing that the Tory leader would be "isolated" and would "alienate" those inside the union and those waiting to join.

He had earlier denounced Hague's warnings of European doom and gloom. "Ever since I became prime minister, at every summit I have ever attended there have been dire warnings of the disasters that would befall us," said Blair. "When we came to this summit we were told we would lose on defence, lose on social security and come under pressure on tax. In fact the whole of this summit has been an exercise in getting the best out of Europe for Britain."

Hague, however, demanded that Blair admit that the Nice treaty represented a significant step towards the creation of an EU superstate. "The prime minister emerged with a treaty that takes Europe in the wrong direction and a Conservative government will not ratify it as it stands," he said.

Hague said the treaty "continues the ratchet of integration making enlargement less and not more likely".

The Tory leader claimed that the erosion of the national veto in 23 areas, the charter of fundamental rights, and the agreement of a "Euro army" represented three further significant steps towards the creation of a superstate.

Instead, Hague said the Nice treaty should have removed the real barriers to expansion - most notably the reform common agricultural policy.

Hitting back Blair said the chasm which exists between the two parties over Europe will be at the heart of the general election campaign. "This is an argument we shall win as it is in the national interest," he told the Commons.