WASHINGTON -- President Bush suggested Friday it may be time to send international peacekeepers into Sudan's war-torn Darfur region over the objections of the government in Khartoum.

"What you'll hear is, well, the government of Sudan must invite the United Nations in for us to act," Bush said. "Well, there are other alternatives, like passing a U.N. resolution saying we're coming in with a U.N. force in order to save lives."

More than 200,000 people have been killed in Darfur and over 2 million have fled their homes since 2003 when ethnic African tribes revolted against the Arab-led government. The government is accused of unleashing brutal Arab militiamen known as janjaweed in the remote western province.

The mandate for a weak African Union peacekeeping force, which hasn't been able to stop the violence, expires next month.

British Prime Minister Tony Blair called the situation unacceptable, and he urged international pressure on the Sudanese government and rebels to stop fighting immediately.

"Last May, we hoped the signature of the Darfur Peace Agreement by the government of Sudan and one rebel group would set Darfur on the road to peace," Blair said in a statement released early Saturday in London. "The non-signatory rebel groups must now accept it. And the government of Sudan must stop its military campaign."

Meanwhile, the resistance by some rebel groups to sign on to a May peace agreement to end the long conflict has prompted the government to ratchet up the fighting again. As the crisis deepens, many believe Darfur is poised for a catastrophic escalation in atrocities.

A Security Council resolution passed in August, aimed at strengthening the peacekeeping force, would hand it over to a better-funded, larger and more well-equipped U.N. mission. But the resolution is unlikely to take effect without the consent of the Sudanese government, something nations including the United States have worked -- without success -- to acquire.

Sudan's President Omar al-Bashir says a switch in command would violate the country's sovereignty and has warned that his army would fight any U.N. forces sent to Darfur.

At the State Department, Assistant Secretary Kristen Silverberg said the United States insisted that last month's resolution permit deployment of new peacekeepers over Sudanese objection.

"We think that the likelihood of ending the violence is much better if we have support and cooperation from the government of Sudan," she told reporters. "But it's not required."

But Bush, bringing up the subject as an example of general frustration with the world body, appeared angry that "the United Nations hasn't acted" on Darfur and wants to see a "more robust" effort. His comments suggested the possibility of a new, tougher resolution that would explicitly bypass approval from the Sudanese government.

"There's genocide taking place in Sudan. And it breaks our collective hearts to know that. ... I'm troubled by reports I hear about escalating violence," the president told reporters during a Rose Garden news conference. "Now is the time for the U.N. to act."

Secretary of State Condoleezza Rice will gather diplomats from several countries to discuss Darfur during the United Nations General Assembly session that begins next week, Silverberg said. The participants and the agenda are not yet set.

It is generally thought that the United States does not support including American troops in the peacekeeping force, instead favoring the participation of NATO forces which would provide logistical and other support to any stepped-up mission.