NEW YORK - The United States will announce new sanctions and step up pressure for U.N. Security Council action against Myanmar, where protesters are marching against the military rulers, U.S. leaders said on Monday.

President George W. Bush will unveil more sanctions against Myanmar in a speech at the United Nations on Tuesday, White House national security adviser Stephen Hadley told reporters on Air Force One on the way to New York.

"He is going to announce that there will be additional sanctions directed at key members of the regime and those that provide financial support to them," Hadley said. Bush arrived in New York to attend the U.N. General Assembly.

"He is going to announce that there will a visa ban to key individuals associated with the negative activities of the regime, including their families."

Separately, Secretary of State Condoleezza Rice told Reuters in an interview that Washington would step up pressure for the U.N. Security Council to take action.

"The international community's got to stand up much more than it has," Rice said. "I think what the Burmese (Myanmar) junta is doing is just a reminder of how really brutal this regime is."

"The Security Council shouldn't allow this to continue and I think you'll see us pressing more for Security Council action," Rice added.

PROTESTS

Tens of thousands of people joined Buddhist monks on marches in Myanmar's former capital Yangon on Monday in the biggest demonstration against the ruling generals since they crushed student-led protests nearly 20 years ago.

What began as anger at sudden steep fuel price rises last month has become a wider movement against the generals.

The Security Council, however, has been divided about action against Myanmar. In January, China and Russia vetoed a resolution calling for Myanmar to stop persecuting minority and opposition groups and take concrete steps toward democracy.

They argued the council was exceeding its mandate by involving itself in a human rights issue handled by other bodies.

But Rice said: "I think there's a new dynamic in what the world is seeing in Burma and the international community ought to be supportive of it."

She said she hoped U.N. special envoy for Myanmar, Ibrahim Gambari, would visit the Asian country but he needed to be able to talk not just to the government but to opposition leaders such as Aung San Suu Kyi.

Gambari briefed the Security Council last week on the situation in Myanmar. He hopes to go to Myanmar next month, but U.N. officials said the timing of his visit was under discussion with the country's government.