A proposed first constitution for the European Union could radically change the way the bloc does business, but only if member states do not scupper its key advances in inter-governmental negotiations later this year.

Tasked with finding ways to keep the EU functioning when it expands from 15 to 25 members next year, a landmark Convention on the Future of Europe completed a draft constitution last Friday offering a streamlined system for taking decisions.

Former French President Valery Giscard d'Estaing, who headed the unique forum, will present the text to an EU summit in Greece this week and urge governments not to unpick its subtle compromises in talks due to start in October on a new treaty.

"I hope it will not be unravelled because that would be a political mistake," Mr Giscard told a news conference. "I don't think it will be unravelled because that would be a backward step, and we have already examined all the alternatives."

His main weapon in defending the Convention's draft is the almost unanimous consensus built over 16 months behind a delicate package deal of institutional reforms.

The Convention proposed a long-term full-time chairman of the European Council of national leaders, an EU foreign minister and a slimmed-down executive European Commission.

It called for a big expansion in majority decision-making and, perhaps most radically, a change in the voting system that would take far greater account of population size, effectively boosting the power of the largest member states.

In future, decisions on justice and home affairs, and an array of other issues except for taxation and foreign policy, would be decided by majority voting.

"Now we have to convince our governments not to unscramble what we've achieved," Dutch lawmaker Frans Timmermans said.

But 18 of the 28 governments that participated in the forum put down a marker on Thursday that they would seek to retain the complex voting system agreed at the EU's 2000 Nice summit, which give small and medium-sized states disproportionate power.

Nice gave Spain and Poland only two votes fewer than Germany despite having half its population. Luxembourg's 450,000 people have four votes compared to 29 votes for Germany's 82 million.

Under Mr Giscard's plan, a decision would pass if backed by at least half of all member states representing at least 60 per cent of the total population.

"Germany and Turkey would be able to block any decision in the future EU," said Jens-Peter Bonde, a Eurosceptic Danish member of the European Parliament. EU candidate Turkey would be the second most populous country after Germany if it joined.

EU governments' ambivalence about the results of the Convention were mirrored in the annotated agenda for this week's summit circulated to member states on Friday by Greece, which currently holds the rotating presidency.

The key phrase on how strongly to endorse the draft has two alternative wordings which leaders will debate in Thessaloniki.One would designate the draft as "the starting point" for an Intergovernmental Conference that will draft a new treaty, while the other would make it "a broad basis" for those negotiations.

If the first wording is adopted, the Convention may have served as little more than a warm-up act for another marathon haggle between member states rimly clinging to their acquired rights with little regard for the efficiency of the EU.

The EU's six founding members - Germany, France, Italy, the Netherlands, Belgium and Luxembourg - all want the Convention's draft to be the main basis for a new treaty with only minor adjustments in the IGC.

Many other stakeholders had one reason or another for disappointment with the text. Christian Democrats bitterly lamented the absence of any reference to God or Christianity.

A small minority of Eurosceptics argued that the Convention had given birth to a "European superstate", despite new rules that will for the first time give national parliaments a chance to block intrusive legislative proposals from Brussels.

Fervent federalists deplored the retention of national vetos in sensitive policy areas and what many saw as a weakening of the supranational European Commission.

Mr Giscard argued passionately that his draft was the only plausible compromise between big and small states, and federal and inter-governmental institutions, reflecting the dual nature of the EU as a hybrid of states and peoples.

Political analysts say it may offer the best hope of a grand institutional bargain that could keep the EU running for decades to come.

"Europe badly needs a compromise acceptable to both large and small states - but one that improves both EU legitimacy and effectiveness," said Steven Everts and Daniel Keohane of the London-based Centre for European Reform.

Key changes proposed in draft constitution

A 105-member Convention on the Future of Europe last Friday completed the main part of a draft constitution designed to allow the European Union to function more effectively after it expands into eastern Europe.

Following are the key changes to EU institutions the forum's leader, former French president Valery Giscard d'Estaing, will propose to EU leaders at a summit in Thessaloniki, Greece, on Friday and Saturday.

¤ The European Council, grouping national leaders, would elect a president or chairman for up to five years to prepare summits and plot the EU's broader agenda, replacing the existing six-month rotation of the presidency among member states.

¤ Full membership of the executive European Commission would be capped at 15, selected according to a principle of strict rotation to ensure the equality of all states. The Commission president, elected by the European Parliament on a proposal from the European Council, could appoint up to 15 associate commissioners without voting rights.

¤ A new EU foreign minister would conduct the bloc's common foreign and defence policy, sitting in the Commission with access to its resources but answerable to member states.

¤ Decision-making on most issues would be by majority vote, with a greater role also for the European Parliament. But member states would retain their right of national veto in politically sensitive areas such as taxation and foreign policy.

¤ The voting system proposed would mean decisions pass if backed by at least half of the member states, representing at least 60 per cent of the EU's total population.

¤ A solidarity clause would require member states to provide mutual assistance in case of terrorist attack. It would also allow those states that wished to subscribe to a mutual defence clause, despite British reservations.

¤ Members of the euro single currency would be able to set and police their own economic policy guidelines and enforce budget deficit limits without non-euro states' involvement.

¤ The Commission would be empowered to issue warnings to eurozone countries whose deficit was approaching the EU limit without having to seek ministers' agreement.

¤ At least one million EU citizens spread across several member states could require the Commission to submit a proposal on matters on which they believe the Union should act.

¤ The EU would have a "legal personality", allowing it to sign international treaties.

¤ Member states may create, by unanimous decision, a European public prosecutor to combat cross-border crime and terrorism.

¤ Any member state would have the right to quit the EU of its own free will after giving notification of its intention.