Serbia on Thursday denounced any unilateral declaration of Kosovo's independence as "invalid and void," just days before the breakaway province is widely expected to secede.

The Serbian government's strongly worded declaration was issued hours before the United Nations Security Council is to meet in New York to discuss Kosovo.

"Such a [move] would represent a flagrant and unilateral act of secession of a part of the territory of the Republic of Serbia, and is therefore invalid and void," the Serbian government said in a statement.

Meanwhile, Serbian Prime Minister Vojislav Kostunica said his country would not be humiliated by a "puppet" state within the territory of the former republic of Yugoslavia.

The government demanded that the Security Council "immediately annul" any Kosovo declaration of independence and denounced a European Union plan to dispatch a 1,800-member police and judiciary mission to Kosovo.

The 100,000 Serbs living in Kosovo will remain "citizens of Serbia and have the full right not to recognize any illegal declarations of unilateral independence" by Kosovo's Albanians, the Serbian resolution said.

Although the province formally remains part of Serbia, Kosovo has been occupied by UN and NATO forces since 1999, when a 78-day NATO-led air war forced out Serbian troops that were killing and expelling the Albanian majority in a crackdown on separatists.

Serbia wants to keep hold of Kosovo, which it considers the cradle of its medieval statehood and religion.

Serbia declaration 'irrelevant': legislator

In the provincial capital Pristina, a member of Kosovo's parliament said the Serbian resolution would have no bearing on Kosovo's intention to declare independence.

"What Serbia does is irrelevant," legislator Vlora Citaku said. "Serbia can only invalidate decisions of its own assembly. Kosovo has its own path, and one that is internationally supported."

The U.S. and most EU nations support statehood for the UN-run province, where 90 per cent of the population of two million is ethnic Albanian.

However, Serbia's traditional ally Russia opposes recognizing Kosovo statehood, calling it a dangerous precedent to set for separatists worldwide.

Speaking Thursday, Russian President Vladimir Putin said his government had a "ready-made plan" in case the West recognized Kosovo's declaration of independence, which he dubbed "not moral and not legal." 

With a Kosovo declaration imminent, Serbia already has endorsed its own secret plan to be implemented when the province declares independence.

The plan is believed to include retaliatory steps to keep Serb-populated areas under Belgrade's control — a move that would result in a de facto partitioning of the province.

The plan contains no provisions for military action against Kosovo, now policed by 16,000 NATO troops.

With files from the Associated Press