PRISTINA (AFP) -- Kosovo's parliament on Thursday denounced as a referendum on Serbia's new constitution, which declares the UN-run province to be an integral part of Serbia.

"The assembly condemns assigning Kosovo in the preamble of the new Serbian constitution as well as conducting the referendum on it on the territory of Kosovo," it said in a declaration, adding such a move was considered as "constitutional aggression".

"Serbia's referendum in Kosovo is illegal, therefore it cannot have any legal effect," it said.

Serbia's parliament unanimously approved the new constitution on September 30 as a signal that it would not give up Kosovo ahead of a decision on the future status of the province expected later this year.

A referendum on the new constitution will be held across Serbia on October 28 and 29.

UN-backed negotiations on Kosovo's future began in February, but ethnic Albanian and Serbian leaders have so far failed to reach agreement on any key status questions.

In the absence of an agreement, the top UN mediator in the talks, former Finnish president Martti Ahtisaari, is expected to make his recommendations for Kosovo's status to the United Nations next month.