BEIJING — McDonald's, Coca-Cola and other sponsors paid tens of millions of dollars to link their names with the Beijing Olympics. Now they're trying to mollify activists pressing for change on Tibet, Darfur and other issues, without angering China.

They have expressed concern over Tibet. Some talk privately to Beijing organizers. But sponsors insist they should stay out of politics.

"We all have to be careful about how we talk about this," said Chris Renner, president for China of sports marketing consulting firm Helios Partners. Its clients include sponsors Volkswagen AG, computer maker Lenovo Group and mining giant BHP Billiton Ltd.

The Olympics almost always attract activists interested in leveraging the popular event to publicize their causes.

At the 1996 Atlanta Games, sponsors faced boycott calls after a county where the beach volleyball event was to be held enacted a measure deemed anti-gay. In Sydney in 2000, there were protests about the environment and Australian aboriginal rights.

But the Beijing Games have generated more heat, in part because of an array of activist groups long critical of China's policies — and newer ones focused on its economic and diplomatic clout.

"Everybody knows we're pretty much on the biggest platform you can pick," Renner said.

Sponsors were already on the lookout for controversy over Sudan, a diplomatic partner and Chinese oil supplier, as well as press freedom, human rights and Tibet.

After protests last week by Tibetans against Chinese rule — and Beijing's crackdown — sponsors said they were watching events closely.

Likely to face immediate pressure could be Lenovo, Coca-Cola and South Korea's Samsung Co., the three sponsors of the Olympic torch relay. The worldwide trek begins this month and will pass through Tibet and up Mount Everest.