Serbia's parliament has unanimously approved a new constitution that claims sovereignty over the UN administered province of Kosovo.
The proposed constitution will be put to a referendum
The move, passed during a special session of parliament, opposes calls for the ethnic Albanian majority in Kosovo to be given independence.
Kosovo has been run by the UN since Nato intervened in 1999 to stop Serbia expelling the ethnic Albanian majority.
The proposed constitution will now face a referendum before it becomes valid.
Serbia's Prime Minister, Vojislav Kostunica, has indicated a referendum would also be followed by early elections, although he has not specified a date.
Mr Kostunica said the country's new constitution would "cement the truth that Kosovo always has been and always will be an integral part of Serbia".
He also insisted there was no need to wait for the Kosovo issue to be settled before adopting the new constitution.
The BBC's Nick Hawton says this is a controversial statement, as negotiations on the province's final status are currently under way.
The UN, which has been hosting the talks on Kosovo's status, has said the issue could be resolved this year.