Serbian protesters lashed out against United Nations police Friday as they demonstrated for a fifth straight day against Kosovo's declaration of independence.

UN police fired tear gas at demonstrators who tried to cross a bridge into Kosovoska Mitrovica on Friday while the crowds struck back with glass bottles and firecrackers.

The bridge separates Serb and ethnic Albanians in the divided city -- which has been a lightning rod for tensions in Kosovo's north.

The Serb demonstrators were waving their country's flag and chanting "Kosovo is ours!" in obvious rejection of Kosovo's declaration of independence on the weekend.

There were concerns that Serbia's leaders haven't done enough to quell the violence and authorities may have allowed police to standby as protesters destroyed embassies. Serb officials have denied the allegations.

U.S. Secretary of State Condoleezza Rice had some strong words about what she said was an inadequate response by Serb security forces.

"They had an obligation to protect diplomatic missions and from what we can tell the police presence was either inadequate or unresponsive,'' Rice told reporters Friday.

"We've made very clear to the Serb government that we don't expect that to happen again."

She also suggested that Serbia should accept that Kosovo is independent and that won't change.

"It's time to move forward," she said.

On Thursday, protesters stormed the U.S. embassy in Belgrade, setting fires, throwing Molotov cocktails and breaking windows -- a demonstration that left one dead and 150 injured.

The attack prompted the American ambassador to Serbia to demand on Friday that the government guarantee the safety of foreign diplomatic missions and their personnel.

"We are demanding from the Serbian government that they condemn the violence that took place yesterday and guarantee that it will not be repeated," Ambassador Cameron Munter told The Associated Press.

All non-essential diplomats and their families in Belgrade were ordered to leave Serbia by the U.S. State Department.

Tensions are still high in the region over Kosovo's declaration of independence on the weekend, a move Serbia has refused to recognize.

Kosovo's prime minister said the recent violence is reminiscent of former Serbian leader Slobodan Milosevic's bloody 1998-99 crackdown on ethnic Albanian separatists in Kosovo.

"The pictures of yesterday in Belgrade were pictures of Milosevic's time," said Hashim Thaci, a former guerrilla leader of the now-disbanded Kosovo Liberation Army. "What we saw were terrible things."

Dada Jovanovic, a journalist working in Belgrade, told CTV's Canada AM the massive demonstrations left parts of the city in tatters, though the mood seemed to have calmed down by Friday morning.

"I just went for a walk to see what was happening at the American embassy," she said.

"It was guarded by police, meanwhile there is a lot of sweeping to be done in Belgrade. People are replacing broken glass with new glass, sweepers are cleaning the debris and broken glass from the streets and maintenance workers are repairing traffic lights and road signs that were demolished last night."

Pro-Western politicians have accused hard-line nationalists in Prime Minister Vojislav Kostunica's government of inciting violence in order to express Serbia's anger at Kosovo's move towards independence.

Jovanovic said many Serbian politicians and media are questioning why the government was unable, or unwilling, to stop the angry mobs from targetting foreign embassies.

"I spoke to former Serbian prime minister Zoran Zivkovic and he said police were acting in a way as if someone told them not to react. And he was sure they were told to let them smash all the embassies and then deal with the aftermath," Jovanovic said.

She said the Canadian embassy, which is not far from the American mission, suffered some damage during the riot, with demonstrators throwing beer glasses at the embassy and a car being set on fire near the location.

But that may have been simply due to its location, Jovanovic said, noting that hooligans and looters were smashing everything in sight.

The European Union has said Serbia's negotiations to join the group would be put on hold.

Maj.-Gen (Ret'd) Lewis MacKenzie, who headed Canadian troops in the region during past conflicts, said Thursday's violence didn't come as a surprise.

"Yesterday was unacceptable but it was totally explainable," he told Canada AM. "Recognizing its independence was the worst day for any Serb because they lost their Jerusalem."

"It's pretty emotional stuff and anything that's emotional in the Balkans involves a bit of a demonstration."

Kosovo is considered by Serbs to be the ancient cradle of their state and religion.