Addressing a special party conference in Dublin, Gormley said the internal dialogue on the new EU Reform Treaty, launched by the Greens yesterday, was "an opportunity" for the party to show "we do things differently and better".

The referendum on the EU constitution is expected to cause serious tensions within the Greens. While the party has opposed previous European referenda, senior figures have signalled that it will be backing a 'yes' vote on the new EU Treaty. But the treaty is likely to be opposed by at least some grassroot members.

Stressing the need for party discipline, the environment minister told party members that as the only party to ever hold informed internal debate on EU issues, there was an onus on the Greens to ensure the debate is wellinformed and open. "But, " he added pointedly, "our dialogue must be dignified and respectful of colleagues and the party".

Gormley insisted that the party has "always been a pro-European party" despite the "worst efforts of some rivals to traduce our critical, and sometimes dissonant, approach to the issue".

Delegates were told that the Greens had already made real achievements in government despite being there for only a few months.