The Olympic torch landed amid tight security on Friday in the Thai capital, the latest leg of its world tour, with police saying they are ready to stop any attempt by anti-China activists to put out the flame.

Several groups angry at Beijing's [Images] human rights record and its rule in Tibet [Images] are thought to be planning demonstrations which, if peaceful, will not incur the wrath of authorities, Thai Olympic chief General Yuthasak Sasiprapa said.

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"If they are peaceful, it's OK," he said. "But we will not tolerate any violent or illegal protests. The torch and runners will be tightly escorted by police patrols and motorcycles all along the route."

The torch relay is due to start on Saturday.

Police are preparing for a demonstration of about 100 people outside the regional headquarters of the United Nations, which lies on the 10.5 km route from Bangkok's China Town to a parade ground outside the golden-spired Grand Palace.

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The elite police Special Branch unit, which newspapers say has been consulting the Chinese embassy about security, said it is also trying to prevent members of the Falun Gong religious group, outlawed by Beijing, from demonstrating.

Yuthasak said short-cuts and alternative torch relay routes have been made ready in case of any "unexpected incidents".

The torch has been beset by protests about Chinese rule in Tibet during its long journey from Greece to the Games' official opening in Beijing in August.

On the previous leg of its swing through Asia, India had to deploy 15,000 police to keep at bay protesters from the world's largest community of exiled Tibetans.

Thai Crown Princess Maha Chakri Sirindhorn will host a dinner on Friday night for those taking part in the torch relay.