He says that a failure on Kosovo "could plunge Southeastern Europe back into the violence and instability of the recent past." He didn't elaborate on what he means by "failure."
Tadic's remarks come as the United Nations awaits a report from one of its envoys on whether status talks on Kosovo should start this year.
Kosovo has been a UN protectorate since mid-1999, after a NATO bombing campaign forced Serbian troops out of the province.
For RFE/RL's full coverage of Kosovo, see "News And Features On Kosovo"