The Madrid attacks have cast a long shadow over the summit

Dutch politician Gijs de Vries, who starts work on Monday, will pool the gathering of Europe-wide intelligence.

Terrorism is at the top of agenda at the European Union summit in Brussels, following the 11 March Madrid train bombings which killed 190 people.

EU leaders also agreed to resume formal talks on the bloc's first constitution, seeking to reach a deal by mid-June.

But correspondents say the Madrid blasts, Europe's worst terror attack since the 1988 Lockerbie bombing, have cast a shadow over the summit, pushing other issues to the background.

Q&A: Europe terror tsar Profile: Gijs De Vries Europe's terror challenge

"The threat of terrorism is a threat to our security, our democracy and our way of life in the European Union," said Irish Prime Minister Bertie Ahern, who holds the EU's rotating presidency.

"We'll do everything in our power to protect our people from this threat."

The leaders of the 25 current and future members agreed a number of steps aimed at showing Europe united in the face of terrorism:

• Implementing already agreed counter-terrorism measures, such as a pan-European arrest warrant, harmonising penalties for terrorist crimes and the freezing of assets held by outlawed groups

• Retaining all telecommunications data, including mobile phone records, for an agreed minimum time to enable intelligence agencies to track calls

• Stepping up security at EU ports.

But the BBC's William Horsley in Brussels says persuading EU governments to share more of their sensitive information will not be easy.

There are also significant differences over how to respond to the terror attacks blamed on Islamic militants, as well as how to treat Europe's growing Muslim population.

The EU foreign policy chief, Javier Solana, said shortly before the summit began that more needed to be done to tackle the factors behind terrorism.

"The peace process between the Israelis and the Palestinians, we can also think about India and Pakistan over Kashmir. They are two frozen conflicts that without any doubt have a lot to do with the atmosphere about terrorism that we are living in today, so therefore to try to solve those problems is a must."

Breakthrough hopes

Spain's newly elected Prime Minister, Jose Luis Rodriguez Zapatero, who has threatened to withdraw Spanish troops from Iraq, is not attending the summit as he is yet to form his government.

His election could, however, herald a breakthrough in discussions on the EU's proposed constitution that broke down amid acrimony in December.

Spain and Poland had refused to accept the proposals for a new system of voting on EU decisions.

But Spain's new leaders appear prepared to compromise; the Poles, says the BBC's Chris Morris, are sensing which way the wind is blowing and do not want to be isolated.

"There was a unanimous agreement to finish the negotiations at the latest by the June (17-18) summit," an EU diplomat was quoted as saying by Reuters news agency on Thursday evening.

Streamlining EU institutions is seen as vital if administrative and political gridlock is to be avoided after the 10 new countries join the 15-member bloc on 1 May.

The leaders will also discuss what until the Madrid bombs was going to be the summit's main theme: economic reforms aimed at making the EU the world's most dynamic economy by 2010.