The head of Indonesia's intelligence agency says some foreign aid groups in tsunami-hit Aceh province are "harming the security situation" with their activities.

Intelligence agency chief Syamsir Siregar told The Jakarta Post that the agency was monitoring a number of foreign non-governmental organisations because of their "irregular" activities in Aceh.

The report will likely alarm international aid groups working in Aceh. Some fear they may soon be asked to leave the province, which was closed to foreigners before the December 26 tsunami struck.

The province is home to a long-running separatist war, and the military fears the influx of aid groups could lead to increased international sympathy for the guerrillas.

The government is currently registering all aid groups in the province, and plans to announce a list of those who can remain in a few weeks.

"There are several NGOs that we should ask for clarification," said Siregar in a report on the paper's website. "There are one or two NGOs that are doing other things aside from their humanitarian work.

"I can only say that their activities could harm the security situation in Aceh, as well as the unity of the country," he said, without elaborating.

The government welcomed foreign help in Aceh in the early days of the disaster that killed more than 128,000 people in Aceh and other parts of northern Sumatra Island. Since then it has indicated it wants more control over those working in the province.

Sections of Indonesia's political and military elite blamed international aid groups and the UN for East Timor's break from Jakarta-rule in 1999. The military regularly blames unnamed foreigners for fanning separatist sentiments in outlying provinces.

Most of the 4.2 million people in Aceh have welcomed the foreign help, saying the government alone is unable to rebuild the battered province on the northern tip of Sumatra.

Rebels in Aceh have been fighting a low-level war for independence since 1976 in which more than 12,000 people have been killed. The separatists have welcomed the spotlight the tsunami has thrown on their movement.