President Bush warned Sudan's government on Tuesday that it must move soon to end the deadly conflict in its wartorn Darfur region.

Bush spoke to reporters after meeting with Andrew Natsios, the United States' special envoy to Sudan. Bush said Natsios delivered a "grim report about the human condition" in Darfur after a 10-day trip to the area.

"The government of Sudan must understand that we're serious, when you deliver a message to them on behalf of our government, that we're earnest and serious about their necessity to step up and work with the international community," the president said.

The vast, remote western province of Darfur has suffered from a 3-year-old war that has left some 200,000 people dead and 2.5 million displaced. Sudan's government is accused of unleashing brutal militiamen known as Janjaweed to quell a tribal rebellion against the government.

The U.N. has authorized 20,000 troops to replace an ill-equipped and underfunded force of 7,000 African Union troops in Darfur to enforce a peace agreement, which has not held. But the Sudanese government has rejected the U.N. force, and last week expelled the U.N.'s Sudan envoy, Jan Pronk.

Bush said a "credible and effective" international force is crucial to bringing peace to the region.

"The United States is going to work with the international community to come up with a single plan on how to address this issue and save lives," he said.