Martial law authorities in Indonesia's Aceh have further tightened restrictions on foreign journalists and overseas non-government organisations (NGOs).

In an order printed in Friday's Koran Tempo newspaper, authorities also forbid both foreign and local NGOs from issuing statements or talking to the press without permission from the martial law administrator, Major General Endang Suwarya.

Government forces are in the second month of an all-out offensive aimed at crushing separatist rebels of the Free Aceh Movement (GAM). The order bans tourists from Aceh and says all other foreigners must enter and leave through the provincial capital, Banda Aceh. They must obtain permission from the justice ministry before travelling to the province and on arrival must report to the martial law authorities, the order says.

It says foreigners are restricted to cities or major towns. Foreign correspondents who want to leave main towns must be escorted by police or troops.

"To protect safety and security, activity outside major towns and cities will be carried out with armed forces or police troops," the order says.

All foreigners in Aceh are forbidden from contacting or giving any assistance to GAM and its sympathisers. Foreign NGOs are banned from representing Indonesian aid groups and vice versa, the order says.

Earlier this week a senior US official said Washington has urged armed forces commander General Endriartono Sutarto and other officials to allow NGOs and the press to operate freely in Aceh.

"We have made clear that more transparency not less transparency is needed in Aceh," said the official, who requested anonymity.