BEIJING — The Olympic flame headed to Kazakhstan today to start a monthlong global tour expected to be a magnet for protests against China, even as the communist leadership hoped to bask in international praise.

The flame left on a chartered plane after an elaborate kickoff ceremony held under tight security in host city Beijing. It will make 21 stops before returning to mainland China on May 4.

Activists in London, Paris and San Francisco have pledged to disrupt the relay to bring attention to causes ranging from Tibetan independence to the crisis in Sudan's Darfur region. But Kazakhstan and then Turkey on Thursday could also be flash points for members of China's Muslim Uighur minority living abroad.

The People's Daily, the official Communist Party newspaper, warned in an editorial today that troubles lie ahead in the four months before the Aug. 8-24 games.

"With the opening of the Games approaching, the burden on our shoulders is heavier and the task tougher," it said. "We must keep a clear head, improving our awareness of the potential dangers, and bravely facing all the difficulties and challenges."

But the commentary said China is prepared for the difficulties because "to successfully host the Olympics is the wish shared by 1.3 billion Chinese people."

Yesterday's ceremony to rekindle the Olympic torch went off seamlessly in Beijing's closely guarded Tiananmen Square — with dancers in brightly colored uniforms, flower-toting children and confetti. The flame had been carried from Greece in a lantern aboard an Air China flight.

President Hu Jintao presided over the ceremony broadcast to the world on state television. About 5,000 people attended the invitation-only event, though hundreds of seats were left vacant, filled only with plainclothes security agents in black jackets.

The 85,000-mile torch relay is a record, meant to showcase China's growing economic and political clout. But the Olympic games have also focused attention on China in the wake of a deadly crackdown on protests in March in Tibet, the biggest challenge to Chinese rule in the Himalayan region since 1989.

The unrest has drawn intense international scrutiny of Beijing's human rights policies, causing embarrassment and frustration for China.

China has consistently blamed the Dalai Lama, Tibet's exiled spiritual leader, and his supporters for inciting protests that began March 10 in the Tibetan capital of Lhasa. The initially peaceful marches exploded into violence four days later.

Speaker of the House Nancy Pelosi urged President Bush to consider boycotting the opening ceremony of the Beijing Olympics as a symbolic gesture against China's crackdown on protesters in Tibet.

"I think boycotting the opening ceremony, which really gives respect to the Chinese government, is something that should be kept on the table," Pelosi said in an interview taped for airing today on ABC television. "I think the president might want to rethink this later, depending on what other heads of state do."

However, Pelosi, a longtime critic of China's human rights policies, said she does not support boycotting the full games. The White House has said that Bush would not boycott the Olympics, saying they are a sporting event, not a political one.