ABUJA, Nigeria (CNN) -- U.S. Secretary of State Hillary Clinton on Wednesday visited Nigeria, warning it could be a target for al Qaeda.
Nigeria is the fifth stop in Hillary Clinton's visit to Africa, to be followed by Liberia and Cape Verde.
The country has been racked by violence between Christians and Muslims, with hundreds having died in riots over the past several years.
"Al Qaeda has a presence in Northern Africa," Clinton said. "There is no doubt in our mind that al Qaeda and like organizations that are part of the syndicate of terror would seek a foothold anywhere they could find one, and whether that is the case here or whether this is a homegrown example of fundamentalist extremism -- that's up to the Nigerians to determine."
Clinton met President Umaru Musa Yar'Adua and other leading politicians in the capital Abuja, the latest stage on an 11-day African tour designed to show U.S. commitment to the continent.
In a town hall meeting she talked about the importance of democracy, making a reference to her own unsuccessful run for president last year.
"I have won some elections and I have lost some elections. And in a democracy there have to be winners and losers," she said, before looking ahead to Nigeria's next elections.
"Part of creating a strong democratic system is that the losers, despite how badly we might feel, accept the outcome, because it is for the good of the country we love," she said.
"And of course in my country the man that I was running against, and spent a lot of time and effort to defeat, asked me to join his government. So there is a way to begin to make this transition that will lead to free and fair elections in 2011,"
Nigeria is "the most important country in sub-Saharan Africa" and one of the most corrupt, according to a senior official on the trip.
It is a major oil and gas producer, one of the largest suppliers to the American market, said Johnnie Carson, assistant secretary at the State Department's Bureau of African Affairs.
"You know the raw numbers, $300 billion, 2 million barrels of oil," Clinton said. "They're staggering. But they don't tell you how many hospitals and roads could have been built. They don't tell you how many schools could have been opened or how many Nigerians could have attended college or how many mothers might have survived childbirth if that money had been spent differently."
Clinton opened her Africa trip in Nairobi, Kenya, then went to South Africa, Angola and the Democratic Republic of Congo. She will travel next to Liberia and Cape Verde.
The Obama administration is also using Clinton's tour to promote development and good governance.
Clinton brought an offer of help Tuesday for victims -- especially victims of sexual violence -- in Africa's longest war, a regional conflict that's dragged on for more than a decade.
"We want to banish the problems of sexual violence into the dark past where it belongs," she said during her visit to the Democratic Republic of Congo.
In a meeting with leaders of nongovernmental organizations, Clinton said the United States will provide "more than $17 million in new funds to prevent and respond to gender and sexual violence."
On Monday, Clinton had delivered a blunt message to Prime Minister Adolphe Muzito when he hosted a dinner in her honor.
"There must be an end to widespread financial corruption and abuses of human rights and women's rights," she said. "There must be an improvement in governance and the respect for the rule of law."
The United Nations estimates 200,000 women and girls have been raped in Congo since war broke out 12 years ago.