(CNN) -- Secretary of State Colin Powell arrived in Khartoum, Sudan, Tuesday, where he will urge the Sudanese government to bring a quick resolution to the crisis in the Darfur region.

On board the plane before he arrived in the capital, Powell said he hoped to give the government a direct message about how the United States sees the horrific situation.

More than a million people in the Darfur region have been displaced since last year after their villages were attacked by government- supported militias.

Several international human rights groups estimate that 15,000 to 30,000 civilians have died in Darfur since fighting broke out in February 2003.

President Bush is "deeply disturbed" by the humanitarian crisis in Sudan and calls upon all parties to"adhere to the cease-fire" and "end the crisis now," a White House statement said.

White House spokesman Scott McClellan also urged the "free movement of humanitarian workers and relief supplies" and for all parties to work in "good faith toward a negotiated settlement."

Powell told reporters that unless the situation is resolved, it threatens to destroy all progress made in U.N.-led peace negotiations between the warring factions.

He also warned of diseases spreading through the refugee camps, characterizing them as death sentences for many of the displaced.

Powell said he hoped that video of the crisis would move the American people, who have so far paid little attention to the situation.

The United States has delivered $116 million in assistance already and has pledged a total of $300 million, according to a statement from McClellan.

On Wednesday, Powell will meet with Darfur tribal and political leaders in the morning at some of the refugee camps, and later with United Nations Secretary-General Kofi Annan in Khartoum.

Annan has described the situation as the world's worst humanitarian crisis.

Powell's visit to the country is the first by a U.S. secretary of state since 1978.

When asked about the possibility of a U.N. peacekeeping force in the region, Powell said that option was being studied, but that it would be better for the Sudanese government to take control.

The conflict in Darfur began last year when black Sudanese rebels attacked government property, accusing the government of neglecting Darfur in favor of the Arab population in Sudan.

The government responded by setting up an Arab militia, known as the Janjaweed, to put down the rebellion. The warring factions recently agreed to a cease-fire but violence between them has continued.