Troops took up positions in the heart of Georgia's capital, Tbilisi, on Thursday to enforce a state of emergency imposed after a violent crackdown on anti-government rallies.

President Mikhail Saakashvili, facing angry demonstrations calling for his resignation, announced a 15-day state of emergency late Wednesday after riot police used tear gas, rubber bullets and water cannons against thousands of protestors.

The crackdown followed six days of protests in front of Parliament - Georgia's worst political crisis since the pro-Western Saakashvili was elected nearly four years ago.

Nearly 100 people hurt during the clashes remained hospitalized Thursday, the Health Ministry said.

The American-educated Saakashvili, who is trying to shake off Russian influence and integrate the ex-Soviet republic with the West, accused Moscow of fomenting the protests and expelled three Russian diplomats.

In protests that began Friday, demonstrators initially called for changes in the dates of planned elections and the electoral system. But after Saakashvili rejected their demands and accused

their leaders of serving the Kremlin, they made his resignation their central aim.

In a nearly 30-minute televised address late Wednesday, Saakashvili said he regretted the use of force, but argued that it was necessary to prevent the country from sliding into chaos.

"Everyone has the opportunity to express their protest in a democratic country and I, as a democrat, have always defended the right of people to protest ... but the authorities will never allow destabilization and chaos in Georgia," he said, flanked by Georgian and EU flags.

The state of emergency must be approved by parliament within two days.

The White House voiced concern over Wednesday's events.

"We urge that any protests be peaceful and that both sides refrain from violence," said Gordon Johndroe, spokesman for the National Security Council. "The government and opposition should engage in a constructive dialogue with each other. We will continue to monitor the situation."

On Thursday, hundreds of Interior Ministry troops clad in khaki uniforms and armed with hard rubber truncheons patrolled Tbilisi's main thoroughfare, Rustaveli Avenue, site of the main protests and of the initial police offensives on Wednesday.

From NPR reports and The Associated Press