Fri Sep 28, 8:37 PM ET

WASHINGTON - U.S. President George W. Bush and British Prime Minister Gordon Brown agreed on Friday to keep up international pressure on Myanmar's rulers, and the White House condemned the crackdown there as "barbaric."

Bush and Brown spoke by video link about "the need for countries around the world to continue to make their views clear to the junta that they need to refrain from violence and move to a peaceful transition to democracy," White House spokesman Scott Stanzel said.

In Myanmar, crowds taunted soldiers and police who barricaded central Yangon to prevent more mass protests against 45 years of military rule and deepening economic hardship in the former Burma.

"The crackdown on peaceful protesters there is quite barbaric," Stanzel told reporters.

State-run television said nine people were killed on Thursday, but Brown told reporters British authorities believed the death toll was "far greater than is being reported."

Brown said Myanmar's government had responded with "oppression and force" to the calls for restraint. "The international community must intensify its efforts," he said in a statement issued before his talks with Bush.

First lady Laura Bush, who has taken an active role in bringing attention to human rights abuses in Myanmar, issued a statement condemning the violence.

"The deplorable acts of violence being perpetrated against Buddhist monks and peaceful Burmese demonstrators shame the military regime," she said.

"The United States stands with the people of Burma. We support their demands for basic human rights: freedom of speech, worship, and assembly," she said. "We cannot, and will not, turn our attention from courageous people who stand up for democracy and justice."

Asked whether Bush and Brown discussed the possibility of encouraging Myanmar's people to overthrow their government if protests grew into a full-scale uprising, Stanzel said: "That would be a hypothetical. ... We certainly support the people who are marching for democracy and peace."

Bush announced tightened sanctions against Myanmar's rulers on Tuesday. Brown said on Friday that Britain was pressing for tougher European Union sanctions.

State Department spokesman Tom Casey on Friday unveiled new sanctions that made more than three dozen additional government and military officials and their families ineligible to receive visas to travel to the United States.

Washington "will add others who bear responsibility for the ongoing attacks on innocent civilians and other human rights abuses," Casey said in a statement.

Jeremy Woodrum of the U.S. Campaign for Burma, an advocacy group based in Washington, said Western countries were "getting it right" by tightening sanctions on Myanmar to put the squeeze on leaders.

The next step was to widen bank account freezes to "target their personal money and make sure they can't bring it in and out of the country," Woodrum said.