U.N. Secretary-General Kofi Annan on Tuesday offered a grim assessment of Kosovo's progress toward stability, saying in a report that the region had fallen behind in efforts to create a multiethnic and democratic society.

Annan's report to the U.N. Security Council said there had been little headway in efforts to achieve a series of benchmarks including the rights of minorities, ending corruption and the return of refugees.

In the report, Annan said he was "seriously concerned that there have been delays or setbacks in most areas," and called on Kosovo's leaders to renew their efforts.

The United Nations has administered Kosovo since NATO's 1999 air war against Yugoslavia. The NATO bombardment forced former Yugoslav President Slobodan Milosevic to end a crackdown on rebel ethnic Albanians in Kosovo and relinquish control over the region.

The U.N. set eight benchmarks for Kosovo that include establishing democratic institutions, protecting minorities, promoting economic development and ensuring the rule of law, freedom of movement and property rights.

The report said the security situation remained fragile and that more work is needed for Kosovo's assembly to become a "central forum for democratic debate."

The assembly still hasn't nominated members of anti-corruption programs, while intimidation of judges and their staff has risen. In addition, Kosovo Serbs are participating in the political process less and less, while few are returning to homes they abandoned during the Kosovo war.

"I strongly urge Kosovo's leaders to renew their efforts to ensure substantive, accelerated and sustainable progress," the report said.

In November, Annan appointed a former president of Finland, Martti Ahtisaari, to lead talks to resolve whether Kosovo should remain part of Serbia-Montenegro, become independent or be given some other status.

Those talks were delayed until February, however, because of the death on Jan. 21 of Kosovo's President Ibrahim Rugova.