The Chinese director of the Bill & Melinda Gates Foundation denied a widespread belief that the upcoming trip of Bill Gates and Warren Buffett to China in late September aims to persuade Chinese billionaires to make charity pledges.

The director of the foundation last Thursday also did not make public who has been invited to a philanthropic gathering with the pair.

Gates, the founder of Microsoft and the foundation, and Buffett, an investment baron, are both among the wealthiest people in the world. They initiated the Giving Pledge campaign in a bid to call on the most affluent families and individuals in the US to donate at least 50 percent of their fortune to philanthropy in their lifetimes or soon after their deaths. The duo announced in August that their action was backed by 40 American magnates.

In China, 50 super-rich Chinese recently received an invitation to a banquet with Buffett and Gates during their visit to Beijing on Sept 29. However, some of them reportedly hesitated to accept the invitation, because they were worried that the cost of the evening would be charity pledges.

Ye Lei, the China office chief for the Bill & Melinda Gates Foundation, said the two had no desire to urge Chinese tycoons to make such pledges.

"The visit has two missions: to advocate philanthropy and to learn about the development of philanthropy in China," Ye said. "They're coming here to see whether in the future there might be some opportunities for cooperation or the establishment of a charitable coalition."

"They want to spend some time in China meeting and exchanging views with people who are either wealthy or experienced in doing charity work here," Ye added.

He further explained that he could not reveal who had been invited out of respect for some guests' request for privacy. Those who want their identities exposed have already announced the news themselves.

Zhang Xin, CEO and co-founder of SOHO China, a real estate developer, was the first to reveal that she received the invitation via her micro-blog on Aug 30.

Zhou Qing'an, a researcher at Tsinghua International Center for Communication Studies, said Gates' and Buffett's trip to China will not be relaxing, because they will encounter a completely different philanthropic environment.

"The conditions here will not make it easy for them to advocate their ideas about charity," Zhou said.

Short histories of wealth accumulation and an incomplete social security system are considered to be two important barriers constraining Chinese rich people's enthusiasm for philanthropic causes, according to Jin Jinping, director of the center for nonprofit organizations law at Peking University.

"Compared to the US, some wealthy people in China seem more concerned about their personal and children's well-being, partly because people tend to worry more about their own education, pensions and medical care," Jin said.

Participation in philanthropy should not be measured simply by how much money a person donates, Jin said.

"Both rich and poor people should enjoy the freedom to take part in charitable activities, rather than being forced to participate," Jin said.