Belgian police swooped on al Qaida terrorist suspects in Brussels yesterday - just as EU leaders arrived for a 27-nation summit.

Last night, 14 suspects were in custody, including one man police believe was planning a suicide attack.

There was no hard evidence the summit was the target, but Belgian federal prosecutor Johan Delmulle said that, with Brussels hosting the summit, officers monitoring the suspects had to act today.

About 250 police conducted 16 coordinated raids in Brussels and one in Liege.

"We don't know where the suicide attack was to take place," Mr Delmulle said. "It could have been an operation in Pakistan or Afghanistan, but we couldn't totally exclude the possibility that Belgium or Europe was the intended target.

"Given that an EU summit was taking place now, we had no choice but to act today."

A Belgian government statement said there had been a real terror risk, adding: "It is more than likely that an attack in Brussels has been prevented."

Only days ago police had intercepted calls making clear one suspect had been given the go ahead to carry out an operation from which he was "not expected to come back" and had said goodbye to his family, "because he wanted to enter paradise with a clear conscience".

Police have linked the raids to similar ones in Belgium a year ago, after which suspects were released without charge within days.

EU leaders were informed of the police raids, but summit security - already routinely high - was unaffected as the meeting tackled climate change, the economic crisis, and the stalled Lisbon treaty.

Tonight, leaders were settling in for late-night talks in a bid to agree climate change targets - a 20% cut in CO2 emissions by 2020. They want to send a signal on Europe's commitment to targets before United Nations climate change talks end in Poznan tomorrow night.

And hopes remained high of approving the terms of a European economic recovery package - despite deep divisions over joint stimulus measures which could cost each member state up to 1.2% of GDP.

Earlier, Prime Minister Gordon Brown dismissed German criticism of his UK economic rescue plan as a matter of "internal German politics".

In a surprise attack, German finance minister Peer Steinbruck derided the headline 2.5% cut in VAT announced by Chancellor Alistair Darling in the Pre-Budget Report while warning that a generation of taxpayers would be saddled with the debt.

In an interview with Newsweek magazine, he described the Government's switch to a "crass Keynesianism" to try to spend its way out of the economic crisis after years of preaching fiscal rectitude as "breathtaking".

But Mr Brown responded: "Actually the German government is investing more. They have just announced a fiscal expansion so that they can invest in public works and help their banks and doing these sorts of things.

"I do not really want to get involved in what is clearly internal German politics here, because they have a coalition in Germany with different political parties.

"The important thing is that almost every country around the world is doing what we have been doing."

The third summit issue - kick-starting the Lisbon Treaty after Ireland's referendum rejection last June - resulted in a draft deal tonight which promises legally-binding reassurances for Dublin of no EU interference in neutrality, tax, and abortion polices, if the Government can get the Treaty ratified by the end of next year.

In effect, Ireland will be expected to hold another referendum by October - with the benefit of being able to offer the public the reassurances pledged at the summit to try to swing a "yes" vote second time round.

The other "carrot" for voters is a change to the Lisbon Treaty guaranteeing in effect that Ireland will continue to have an Irish Commissioner at the EU table.

The draft conclusions make clear EU leaders want the Treaty - which must be ratified by all 27 EU countries - to come into force by January 1 2010.

The agreement came after Irish Prime Minister Brian Cowen set out what support he needs from the rest before risking another referendum.

But the details of how the guarantees are to be enshrined has still to be hammered out before the summit ends tomorrow.