The House of Commons Home Affairs Committee said that the case had not been made for far-reaching changes in the way the EU deals with issues like crime, immigration and terrorism - including proposals to introduce qualified majority voting (QMV).

Instead of wrangling over institutional change, this month's gathering of EU home affairs ministers in Luxembourg should focus on practical measures to improve cooperation between police, judicial systems and other agencies on the frontline of the fight against international crime, the committee said.

Some of the EU's 27 states want to see QMV introduced for justice and home affairs matters, so that a country like the UK could be overruled on measures it opposes.

But in its report, the Home Affairs Committee insisted: "The evidence we have seen does not persuade us that, as things stand at present, there are sufficient benefits in terms of tackling crime, either here in the UK or across the EU, to justify such a major transfer of power away from individual member states."

The QMV proposal is one of the changes which some EU states are trying to salvage from the failed European Constitution, which was rejected by French and Dutch voters in referendums in 2005.

Current EU President Germany is expected to seek to relaunch the constitution at a summit in Brussels on June 21, when the UK will argue instead for a slimmed-down treaty amending some of the Union's institutional arrangements.

But the report warned that the EU is wasting too much of its time arguing over institutional change and not enough on gathering the evidence needed to make a real impact on international terror, organised crime and illegal immigration.

Committee chairman John Denham said: "We have been struck by the way in which the debate about EU action on crime and illegal migration is dominated by different views of the future political shape of the EU, instead of identifying what would be most effective in tackling these major European challenges.

"Much of the debate is taking place without a sound analysis of the problems, or a reliable assessment of the effectiveness of current action. We conclude that the priority should be to develop practical co-operation between police forces, judicial systems and other agencies."