Lhokseumawe – Local residents and human rights officials in Indonesia's Aceh province said yesterday anonymous groups had sought to intimidate them since the discovery of mass graves in the area, the site of a separatist insurgency that peaked in the early 1990s.

On Thursday, Aceh residents found two new mass graves in a forest about 16 kilometres from a highway linking the provincial capital of Banda Aceh to the north Sumatran capital of Medan. The sites are about 10 kilometres from an area known to residents as "skeleton valley", where 10 other mass graves were found.

Residents told a reporter that unknown men had come to their homes and warned them not to speak to reporters or members of non-government organisations (NGOs). Witnesses said local government officials in the town of Biereuen, 60 kilometres west of Lhokseumawe, were stopped by a group of masked men who demanded to know whether they were NGO officials.

They also said that a separatist flag was raised in front of a school in Peudada town, 80 kilometres west of Lhokseumawe, but was immediately pulled down by residents. Peudada residents said they did not know who had flown the Free Aceh flag.