In a brief ceremony inside the empty stadium that hosted the first modern Olympics in 1896, Beijing Games vice-president Yu Zaiqing fired up a small red lantern from the flame lit on Sunday in ancient Olympia, site of the ancient Games.

The lantern will arrive in the Chinese capital on Wednesday, kicking off a domestic torch relay that ends with the Games opening ceremony on February 4 as Beijing becomes the first city to host both Summer and Winter Olympics.

Greek police had cut off access to the stadium hours before and surrounded it with a large number of security personnel for fear of more protests after Tibetan activists broke through a police cordon on Sunday in ancient Olympia to demonstrate just as the flame was lit.

They unfurled a banner reading "No Genocide Games" and a Tibetan flag metres away from where the torch was lit and with officials, including Greece's President of the Republic, looking on.

In a news conference in Athens earlier on Tuesday, human rights activists had urged governments and athletes worldwide to boycott the Beijing Games, saying anything less would make the world complicit in what they called "genocide" by Beijing.

There have been a number of protests in Greece in the past three days, including one on the Acropolis monument with a "Free Hong Kong" banner that led to the arrest of two people. More people were detained in Olympia.

Rights groups and US lawmakers have repeatedly called on the International Olympic Committee to postpone the Games and relocate the event unless China ends what the United States deems ongoing genocide against Uyghurs and other Muslim minority groups.

Chinese authorities have been accused of facilitating forced labour by detaining around a million Uyghurs and other primarily Muslim minorities in camps since 2016.

China denies wrongdoing, saying it has set up vocational training centres to combat extremism.

Australian Associated Press