Euro zone may need treasury, minister, budget, bonds-EU Commission

* EU executive spells out ideas on euro future after debt crisis

* French presidential election gives boost to integration plans

* Merkel, Macron keen to get more cohesive euro zone

* Bigger changes to euro zone could happen after 2019

By Jan Strupczewski

BRUSSELS, May 31 (Reuters) - The European Commission said on Wednesday the euro zone might need to issue collective debt and run a joint budget among ideas for deeper European Union integration around the single currency after Britain leaves the EU in 2019.

In a reflection paper that aims to trigger a debate among euro zone governments, the EU executive spells out ideas on what could be done to deepen Economic and Monetary Union by 2025.

Scenarios of a finance minister managing common euro zone revenue, spending and borrowing had been worked on for months in Brussels, but now appear more likely since centrist former banker Emmanuel Macron became French president this month.

German conservatives dislike an idea they say could mean paying for poorer neighbours or irresponsible policies and are loath to mutualise debt among the 19 euro zone countries.

But Chancellor Angela Merkel, seeking re-election in September, has welcomed Macron's victory and EU officials said they hoped governments might start working on a plan to forge a more cohesive euro zone from next year.

The Commission paper examines possible reforms to the bloc after the 2010-2012 sovereign debt crisis that nearly destroyed it and which triggered a wave of quick fixes for its weak spots.

While some problems have been addressed, there is a lot more EU governments need to do to have an optimally functioning single currency area, the Commission said.

The document, part of a wider series on the future of the European Union, comes as the EU is to start talks with Britain on the terms of its withdrawal - a great setback to European integration but one that will see the euro zone make up nearly four-fifths of the EU's economy, up from two thirds today.

NO BLUEPRINT, JUST IDEAS

The Commission avoids making any clear suggestions as to the evolution of the euro zone, leaving it up to EU governments to decide which of the ideas they like.

But it does say that in the later stages of integration, not least because it would require politically difficult and time-consuming changes to EU treaties, the bloc could establish a euro zone treasury.

The chairman of euro zone finance ministers, the Eurogroup, could be in charge of such a new institution. The job of Eurogroup president itself could be integrated into the Commission, the paper says.