President Georgy Parvanov on Thursday called for a referendum on Bulgaria's bid to join the European Union in 2007, even though parliament ratified the accession treaty earlier this week.

"If there is a question that has to be definitely put to the national vote, that is the question on Bulgaria's accession to the EU," Parvanov said after signing the ratification documents.

He suggested that a referendum be held on the same days that Bulgarians elect their members of the European Parliament.

According to a recent opinion poll, around 70 percent of Bulgarians are in favour of their country joining the EU.

Bulgaria and Romania signed their accession treaty on April 25 in Luxembourg.

Romania has not yet ratified the document, but Bulgaria's outgoing parliament hurried to do so Wednesday before it dissolved itself ahead of legislative elections on June 25.

Romanian President Traian Basescu recently said he too wants a rapid ratification of the treaty by parliament, and was not planning a referendum.

"A referendum would only demonstrate what we already know -- that 90 percent of the Romanians are in favor of joining the EU," he said.

The two former communist countries are still subject to a special "safeguard clause" that can postpone accession if they fail to implement changes to bring them in line with European standards.

The European Commission has criticized progress on anti-trust, reform of the judiciary and the battle against crime and corruption.

The Bulgarian government Thursday adopted a new penal code to be approved by the next parliament.

Justice Minister Anton Stankov said the code "provides for a quicker judicial process ... and creates favourable conditions for solving the severe problems of organised crime and corruption."

Bulgaria has been severely criticised by the European Commission for its slow and inefficient legal system.