WASHINGTON (AFP) - The United States on Tuesday voiced its "disgust" at Ukraine's repression of demonstrators at Kiev's Independence Square, Secretary of State John Kerry said.

Washington "expresses its disgust with the decision of Ukrainian authorities to meet the peaceful protest in Kiev's Maidan Square with riot police, bulldozers, and batons, rather than with respect for democratic rights and human dignity," Mr Kerry said.

"This response is neither acceptable nor does it befit a democracy."

His strong reaction came as Ukrainian security forces stormed Kiev's Independence Square, occupying an area protesters had held for over a week and removing their barricades in a move that sparked immediate international concern.

Opponents of President Viktor Yanukovych's rejection of an EU pact were still holding nighttime protests on the square when elite Berkut anti-riot police and interior ministry special forces moved against them.

Mr Kerry said that respect for basic democratic rights including freedom of assembly was "fundamental to the United States' approach to Ukraine.

"This is a universal value not just an American one. For weeks, we have called on President Yanukovych and his government to listen to the voices of his people who want peace, justice and a European future. Instead, Ukraine's leaders appear tonight to have made a very different choice.

"We call for utmost restraint," Mr Kerry stressed. "Human life must be protected. Ukrainian authorities bear full responsibility for the security of the Ukrainian people."