Brown challenges Tories before MPs debate EU treaty

A two-month campaign to expose Conservative divisions and contradictions on Europe will be launched by Gordon Brown today when he tells pro-European business leaders that global economic turbulence requires Britain to engage with Europe, and not play with the possibility of withdrawal.

Brown will tell a conference organised by the New Europe thinktank that, even in the face of rapid globalisation, our trade with Europe continues to rise, and Europe is as important to the future of Britain as ever. He will be speaking a week before the second reading of the bill which brings the EU treaty into British law, an issue that is going to dominate 21 days of debate on the floor of the Commons in February and March. Brown will face guerrilla opposition from some of his backbenchers, but he has warned that the bill must go through the Commons unamended, or the government will not be able to ratify the treaty.

The Conservatives and some Labour MPs will unite to press for a referendum on the treaty. David Cameron has said that his party will not let matters rest if the treaty is ratified and the Conservatives go on to win the next election. He will return to the issue even if the treaty has been ratified by all other EU states, but he has stopped short of the demand made by some Eurosceptics for a commitment to a referendum.

The Europe minister, Jim Murphy, is hoping to use the Commons debates to expose Tory divisions on Europe.

At the same time ministers will come under pressure to give a commitment in the bill that they will not opt in to future justice and home affairs reforms without allowing MPs a vote.

Under the treaty Britain will be required to decide whether to opt in to a range of justice and home affairs proposals in the future. Brown has indicated there will not be enough time to consult parliament on each opt-in proposal. The prime minister has, however, indicated that any proposal to activate mechanisms in the treaty which provide for further moves to qualified majority voting, but which first require the unanimous approval of EU member states, will have to be subject to a prior vote at Westminster.

The bill also includes a statutory requirement that any future EU amending treaty would have to be ratified through an act of parliament.

In his speech today Brown will seek to focus on the economic advantages of Europe, saying that the European single market gives British businesses access to a market of 500 million people, to cheaper products and services, and to a much wider potential workforce, with a greater range of talents and skills. He will add that EU enlargement - "perhaps Europe's greatest achievement" - has strengthened our stability and prosperity even further.

"But if we are to make the most of the opportunities of the new global economy ... we will need to do more to ensure continued stability and to strengthen and deepen economic reform in Europe."

Brown is preparing to hold talks on economic reform in Europe shortly with Nicolas Sarkozy, the French president, Angela Merkel, the German chancellor, and Romano Prodi, the Italian prime minister.