President Bush Friday demanded that Sudan stop pro-government militias from attacking civilians in the troubled Darfur region of the country. Mr. Bush spoke amid increasing concern about the situation in Darfur, which has been called the world's worst humanitarian crisis.

Mr. Bush said that the Khartoum government has failed to fulfill its promise to disarm the Arab militia known as the Janjaweed. He said the U.S. government has made its position very clear to Sudanese leaders.

The U.S. Congress Thursday unanimously passed a resolution declaring the Darfur violence genocide. U.S. officials are not the only ones speaking out. Speaking in Washington Friday, former Australian Foreign Minister Gareth Evans, who heads the International Crisis Group, accused the Janjaweed militia of carrying out atrocities. Mr. Evans said the militia forces have killed 10,000-30,000 people in Darfur over the past 15 months and the number of dead could soar even higher.

"We simply cannot exclude the possibility that the judgement made very recently by U.S. AID that there could as many as 300,000 people dead by the end of this year and maybe up to one million in the period thereafter," he said. "We cannot exclude the possibility that those predictions will still be realized."

About one million people have been displaced by the violence. The Sudanese government denies that it is supporting the militias and blames the conflict in Darfur on rebel groups seeking greater rights for non-Arabs in the region.

Mr. Evans of the Crisis Group says more international assistance is urgently required for the people of Darfur. He says the world community is not moving fast enough to provide either food or peacekeeping troops. He says only 25 percent of the hundreds of thousands displaced people are getting any humanitarian aid at all.