Belgrade  - The Serbian parliament on Wednesday overcame opposition to open a debate on a crucial pre-membership treaty with the European Union and several other major issues, including Kosovo.

Legislators were discussing ratification of the Stabilization and Association Agreement Serbia signed with EU. The treaty is a major step towards membership, but needs to be approved by all 27 member- states.

Several EU countries warned they would not ratify the agreement until the Serbs arrest Ratko Mladic and Goran Hadzic, the two remaining fugitives wanted internationally for war crimes.

The debate was originally due to start in July, but filibustering by the nationalist opposition forced an early and extended summer recess. It was not clear when the vote would take place.

Also on the agenda are nearly a dozen trade agreements with EU, as well as an energy agreement with Russia, parts of which are claimed by experts as unfavourable to Serbia.

The agreement, which includes the sale of a 51-per cent stake in the national oil monopoly NIS to Russia for 400 million euros (580 million dollars), though auditors estimated the value of the company at more than 3 billion.

Opponents of the deal, among them the G17 Plus party, a junior partner in the ruling coalition, called the sale a giveaway. Critics said Serbia was handing the NIS over in return for Russia's support in the tug-of-war over Kosovo.

Kosovo unilaterally declared independence from Serbia in February and was quickly recognized by leading Western nations, but Russia blocked its promotion to a fully-fledged state in the United Nations.

Though a pro-European coalition replaced the previous government led by the nationalist Prime Minister Vojislav Kostunica, Serbian legislators were also expected to repeat Belgrade's claim of sovereignty over Kosovo. (dpa)