Reports from London say four people have been arrested for forcing their way into the Indonesian embassy in a protest over Jakarta's policy towards the Papuan people.
Some demonstrators forced their way onto the premises to remove the Indonesian flag but were prevented from raising the Papuans' separatist Morning Star flag.
Other demonstrators chained themselves to the embassy railings but police cut them free.
The activists demanded a withdrawal of Indonesian troops from the province, an end to the harassment of human rights groups by the Indonesian authorities and the release of a tribal leader, Benny Wenda.
They also want an independent probe of last November's assassination of the Papuan leader, Theys Eluay.