As China prepares to host a summit with African leaders in Beijing, American experts say they are concerned about Beijing willingness to maintain close relations with pariah states on the continent.

Billboard promoting China-Africa summit

China proudly displays its growing ties with Africa in holding a high-profile summit for African leaders in Beijing. But critics in the United States warn of the negative aspects of Beijing's pragmatic foreign policy.

"The story, I'm afraid, is not a good one. In Africa, as elsewhere in the world, the Chinese government has shown that it is eager to embrace dangerous and or unsavory regimes in order, among other goals, to secure access to oil," said Carolyn Bartholomew, a member of the U.S. China Economic and Security Review Commission, a body that advises Congress. She said China has sought close ties with countries that western countries consider pariah states, such as Sudan, an oil-rich country that has come under international criticism for the ongoing crisis in Darfur.

She accuses Beijing of selling the Sudanese government military equipment that has been used to commit atrocities in Darfur.

The Chinese government has rejected criticism about its sales to Sudan, saying its arms sales are not large enough to destabilize the region.

Walter Kansteiner, who recently served as assistant secretary of state for Africa and is now at the consulting firm, Scowcroft Group, says in the 1960s and 1970s, relations between China and Africa were based on shared political vision.

"It was ideologically driven. It was politically mandated. It was part of the international socialist system of supporting your liberation brothers," he said.

Today, he says, China-Africa ties are largely based on commercial interests.

"It's about raw materials. It's about feeding the industrial base back in China. So, what is this industrial base, and what is it that they need? They need raw materials. They need strategic minerals. They need hydro-carbons. They need iron ore and timber, they need to keep their industrial base alive," he said.

Kensteiner said Washington should be concerned about China's close ties with leaders, such as the president of Zimbabwe, Robert Mugabe.

"Does it worry the U.S. government that China is aiding and abetting Robert Mugabe? Yeah, it does and it should. You know, he's a bad guy, doing bad things to his people. And so, if Beijing is supporting and helping him, from a policy-maker's point of view, that's counter-productive," he said.

Another way China is making friends and allies in Africa is through generous aid donations. Joshua Kurlantzick, at the Carnegie Endowment for International Peace, says China's contributions have increased exponentially in the past decade, reaching $2.7 billion in 2004.

"That's up from about $100 million from a decade before, so that's a substantial increase, and puts China, as a donor on the continent, on league with other donors, including the U.S., France and Japan," he said.

Despite the positives, Chinese efforts to make friends in Africa has not been a completely smooth process. Paul Hare, the executive-director of the U.S.-Angola Chamber of Commerce and a former U.S. Ambassador to Zambia, says he is noticing what he calls a "downside" for the Chinese in Angola, which has become China's main foreign source of crude oil.

"Others claim there is a growing resentment of the Chinese role in Angola, among the Angolans, taking jobs and contracts away from the Angolans, and speak of the Chinese invasion. I think there is some increasing xenophobia against the Chinese," he said.

There are some indications China is taking international criticism into consideration on issues like Sudan, which Carolyn Bartholomew called the Chinese government's "biggest public relations nightmare on the global stage."

In a rare public statement broadcast on Chinese television Thursday, Chinese President Hu Jintao told Sudanese President Omar al Bashir that the Darfur conflict has once again reached what he called a "critical stage." The Chinese president said Beijing understands Khartoum's concerns on Darfur, but said he hopes the Sudanese leader will strengthen dialogue with all parties concerned and help improve the humanitarian situation there.