Plaid Cymru has said it will back the new European Union constitution provided the government meets the party's "green lines".

Senior party representatives announced on Thursday that they would campaign for a "yes" vote in any referendum provided ministers met their key concerns.

Leading Welsh nationalists are due to hold discussions with foreign secretary Jack Straw over the summer.

Plaid said that the Welsh assembly should be consulted by the UK government before the Commission publishes proposals relevant to its powers.

And they called for the devolved parliaments and assemblies in the UK to have a say in whether proposals for EU legislation breach the principle of subsidiarity, which requires decisions to be taken at the lowest legislative level.

The party also called for the UK's devolved territories to have representation on all relevant UK delegations in the Council of Ministers and in other official EU meetings.

Finally Plaid also said that the constitution should be translated into Welsh and that the results of the referendum should be announced separately for Wales, Scotland, England and Northern Ireland.

"Plaid Cymru was the first party in the UK to call for a written European constitution and a binding Charter of Fundamental Rights, therefore, in principle we are in favour of the European constitution," said Plaid's parliamentary leader Elfyn Llwyd.

"For the first time, the powers and structures of the Union will be set out in a single document and we believe the institutional reform is necessary for a growing union of 25 members.

"Having said that, in the next two years, commencing with our meeting with Jack Straw, we will be concentrating on what requests can be made to the UK government in the course of preparing a referendum bill to ensure the people of Wales are fully represented in Europe."

And recently re-elected nationalist MEP Jill Evans said it was vital for the UK government to pledge to consult with the National Assembly for Wales.

"Among other things, we are also requesting that the constitution is translated into the Welsh language, in the same way as it will be translated into Irish and Catalan," she added.

"The very least the UK government could do is to translate this hugely important document into Welsh."