KIGALI, Rwanda — Speaking on soil once stained with the blood of Rwanda’s genocide, President Bush called today on all nations to step up efforts to end “once and for all” the ethnic slaughter in Sudan’s western Darfur region.

The president said America is using sanctions, pressure, and money to help resolve the Darfur crisis that Mr. Bush calls a genocide. But the president, frustrated at the lack of willingness of some other countries to do the same, sought to give his campaign for their increased involvement added weight by making pointed remarks on it from the Rwandan capital.

“The Rwanda people know the horrors of genocide,” Mr. Bush said after meeting with President Kagame. “My message to other nations is: ‘Join with the president and help us get this problem solved once and for all.’ And we will help.”

Rwanda was the first to deploy peacekeepers to the violent Darfur region in a joint African Union-U.N. mission. America has trained nearly 7,000 Rwandan troops and spent more than $17 million to equip and airlift them into the region. America has committed $100 million to train and provide equipment for peacekeepers from several African nations deploying to Darfur.

“I’m not comfortable with how quickly the response has been,” the president said.

Mr. Bush spoke after a somber visit to the haunting Kigali Memorial Centre. Exhibits there tell the story of Rwanda’s 1994 genocide as well as other ethnic slaughter around the world. Mass graves on a trellis-covered hilltop outside hold some remains of about 250,000 people.

Over 800,000 Tutsis and moderate Hutus were shot, clubbed, and hacked to death in just 100 days by extremist Hutu militias incited by the then-government. It ended when Mr. Kagame’s rebel forces ousted the Hutu government.

“It’s a moving place. It can’t help but shake your emotions to their very foundation,” Mr. Bush said after walking through its rooms and gardens. “There is evil in the world and evil must be confronted.”

Later, by Mr. Kagame’s side, Mr. Bush displayed how shaken he was by what he saw. “I just can’t imagine what it would have been like to be a citizen who lived in such horrors, and then had to, you know, gather themselves up and try to live a hopeful life,” he said.

Mr. Bush also pushed Mr. Kagame on the continuing conflict in neighboring Congo, where Rwanda has a troubled history.

Many of the Rwandan genocide’s perpetrators fled afterward into Congo, prompting fears here of a resurgence. As a result, Rwanda invaded Congo in 1998 and the back-to-back multination wars there killed a staggering 5.4 million people and decimated that country. Rwanda was accused of plundering Congo’s resources before the war ended and it pulled its soldiers out in 2002.

Sporadic violence has continued to plague Congo’s volatile no-man’s-land in the east since, and some suspect Rwanda of still supplying armed groups there. Mr. Bush said he and Mr. Kagame talked “for a long time” about last year’s peace accord between Rwanda and Congo and last month’s fragile cease-fire forged between Congo’s government and several armed groups. America helped broker both.

“The most important thing is to get results for the agreement and that’s what we discussed today, on how to help bring peace to this part of the world,” Mr. Bush said.

Mr. Bush also drew a parallel to Kenya, where long-simmering ethnic grievances are playing a role in postelection bloodshed.

December presidential elections, which foreign and local observers say were rigged, returned President Kibaki to power and unleashed weeks of fighting. Much of the violence — shockingly brutal in a country once considered among Africa’s most-stable — has pitted other ethnic groups against Mr. Kibaki’s Kikuyu tribe, resented for traditionally dominating politics and business.

“Now I’m not suggesting that anything close in Kenya has happened — is going to happen — anything close to what happened here is going to Kenya,” Mr. Bush said. “But I am suggesting there’s some warning signs that the international community needs to pay attention to.”

Mr. Bush dispatched Secretary of State Rice to Nairobi yesterday to meet with Mr. Kibaki, the opposition leader, and a former U.N. chief, Kofi Annan, who is mediating peace talks.

The Rwanda massacre haunted the international community, including America under President Clinton, for not recognizing the danger and intervening faster.

Mr. Bush, pressed about what role his successor can play in preventing genocide, said the lesson is to watch for warning signs — and act.

“I would tell my successor that the United States can play a very constructive role,” Mr. Bush said. “I would urge the (next) president not to feel like U.S. solutions should be imposed upon African leaders. I would urge the president to treat our — the leaders in Africa — as partners. In other words, don’t come to the continent feeling guilty about anything. Come to the continent feeling confident that with some help, people can solve their problems.”

Mr. Bush stood by his decision not to send American troops to Sudan, but used some of his strongest language to date in blasting the slow pace of the international peacekeeping plan.

“If you’re a problem solver, you put yourself at the mercy of the decisions of others, in this case, the United Nations,” Mr. Bush said. “And I’m well known to have spoken out by the slowness of the United Nations. It is — seems very bureaucratic to me, particularly with people suffering.”

Summing up his advice to the next president, he said: “Take problems seriously before they become acute, and then recognize that there’s going to be a slowness in the response if you rely upon international organizations.”

Mr. Kagame said America should not be viewed as the world’s problem-solver.

“The problems and the solutions for those problems should not be taken away … from places where they’re taking place,” he said.

Before leaving for Ghana, Mr. Bush and the first lady visited a school where they spoke with children, who are members of an anti-AIDS club, working to spread the word about preventing the disease. The two dozen children, all dressed in white shirts and khaki pants, chatted for about 20 minutes with the Bushes, who sat outside on a hillside in low-slung, hand-carved wooden chairs.

“Thanks for being leaders,” the president told them.