There are concerns for the welfare of a prominent Papuan leader allegedly beaten by Indonesian security forces in the aftermath of a pro-independence rally last month.
Forkorus Yaboisembut, a senior figure in the Papua Customary Council, was arrrested along with four others, Mr Yaboisembut is now facing charges of treason.
While most of those arrested have been released, Mr Yaboisembut, remains in custody.
A medical officer who visited the 72-year-old in custody this week reported he had been badly beaten on his chest.
Another council member, Dominikus Surabut, had severe injuries to his back, according to the medical officer who did not wish to be named.
The report could not be verified as foreign journalists and non-government organisations, including human rights groups, are banned by the Indonesian government from travelling to Papua.
A spokesman for Human Rights Watch says he has concerns for the welfare of the activists, but in particular Mr Yaboisembut and Mr Surabut.
He also criticised the use of force by Indonesian police and military at last month's rally.