Some of China's billionaires are slow to RSVP to a charity dinner invitation from two of the world's richest men -- Warren Buffett and Bill Gates, who are making a philanthropic tour to Beijing late this month.

The reason: The super-rich are unsure if the banquet, scheduled for September 29, will turn out to be an occasion at which they have to make charity pledges, the Economy Observer reported yesterday.

Though the dinner is billed as a "closed-door private gathering" about charity, a few people who received invitations from the Beijing branch of the Bill & Melinda Gates Foundation declined to attend. Others called to check whether they would be asked to donate at the dinner before agreeing to come, Ye Lei, a project manager of the branch, told the newspaper.

The foundation reportedly is planning to ask about 50 of the wealthiest Chinese to the banquet and has been approaching them in the past 10 days.

The invitation list was made according to the guests' rankings on the Forbes magazine list of the world's richest people, the newspaper added.

The biggest concern on the minds of the invited was that "they felt they might be embarrassed at the party," Ye told the Beijing-based newspaper.

Ye assured them that the tour has no intention of persuading people to donate or to sign up for the Giving Pledge campaign as it did for their American counterparts in the US.

Gates and Buffett may send a written letter to each of those invited this week to clarify that the charity dinner was just an occasion to "meet new friends, share ideas and look for cooperation partners," and will not put any pressure on them.

In June, Buffett and Gates persuaded 40 US billionaires to join their charity campaign, named the Giving Pledge.

It asks those who commit to give away at least half their fortune during their lifetime or after death, and to publicly state their intention in a letter explaining their decision.

Buffett said he personally pledged "more than 99 percent of his wealth will go to philanthropy during lifetime or at death."

The fortune of the head of the Berkshire Hathaway investment group was estimated this year at US$47 billion.

Gates has an estimated US$53 billion, which places him second on the Forbes list. Buffett ranks third.

Charitable giving is not a novelty in China.

But the tradition declined in recent years.