Brussels - In a move hailed by environmentalists, the European Commission agreed Wednesday to tighten rules on testing genetically-modified foodstuffs before they can go on EU shelves.

But militants against biotech foods, who claim they threaten both human health and the environment, said that the European Union's food safety agency must be even more strict in policing food coming into the continent.

"The European Commission has taken a positive step by seeking to improve GMO risk assessment in the EU," said Eric Gall of Greenpeace after the move on genetically-modified organisms (GMOs) by the EU's executive arm in Brussels.

"But it must make sure that the European Food Safety Authority is immediately subject to mandatory guidelines on how to evaluate the risks of GMOs," adding that GMO authorisation should be suspended pending this change.

The Brussels announcement came after EU environment ministers last month criticized the Italy-based European Food Safety Authority (EFSA) for delivering systematically positive assessments of GMO applications.

The EFSA greenlight frequently clashed with the views of national food safety agencies in EU member states, where public skepticism about what critics call Frankestein foods varies widely.

At the EU commission's request, EFSA will from now on have to detail publicly the exact reasons "for rejecting scientific objections from national authorities."

The agency, set up in 2002 in the Italian city of Parma, will also have to carry out more extensive tests on potential long-terms risks of GMOs and their impact on biodiversity, key aspects demanded by environmentalists.

The EU commission trumpeted its move as a way improving public trust on the issue of GMOs, which is hugely divisive in Europe.

"We want to increase the confidence of (EU) member states and of public opinion in the GMO authorization process," said Philip Tod, spokesman for EU environment commissioner Markos Kyprianou.

Despite the lifting of a de facto European moratorium on GMOs in 2004, no GMO variety has been authorized to be grown in the 25-nation bloc.

But three varieties -- one potato and two types of maize -- have been approved by EFSA, and are now awaiting a green light from EU experts in Brussels.

The EU commission said its move made no fundamental difference to EU legislation on biotech foods, but was simply a "practical improvement" in how the bloc deals with the issue.

The United States, Canada and Argentina, three of the biggest exporters of GMOs, hauled the EU before the World Trade Organization over its pre-2004 moratorium, and a ruling handed down in February went in their favour.

But the commission did not propose changing the widely-criticized way decisions on GMOs are made in Brussels.

For the moment, once EFSA has given its assessment, the commission makes a proposal to experts from EU member states, then to ministers if no agreement is reached.

But since the end of the moratorium the 25 governments have never achieved the required qualified majority required to agree or reject an application, leaving it up to the EU commission to make the final decision.

Austria, which is fiercely anti-GMO and which holds the EU presidency until June, has called for decisions to be made by simple majority, making it easier to block applications. But there is little chance of this change being agreed.