Police in Indonesia say they have arrested 13 men suspected of taking part in training for Islamist militants in a remote part of Aceh province.
The men have been detained in several raids since 22 February, when the first four were arrested in Aceh's mountains.
Rifles and thousands of bullets were seized in the raid, along with DVDs on the Bali bombings of 2002 that killed more than 200 people, police said.
But it is unclear to which group the suspects might belong.
Police are still searching for a number of people who fled the raids, but say they are investigating possible links with Jemaah Islamiyah (JI), which was blamed by the authorities for the Bali attacks.
However, analysts say JI has not previously been active in Aceh.
Sidney Jones, the head of the International Crisis Group in Indonesia, says the Islamist militant group has never had a base in the province, even though the executed Bali bomber Imam Samudra originally came from there.
"The group does not appear to be mainstream JI, but a composite group," she told the BBC.
"It's not clear they were up to anything other than training," she added. "Many, if not most, appear to be non-Acehnese."
Aceh is home to its own separatist nationalist group, GAM, which became a political party following a 2005 peace agreement and now has members running local governments.
A recent International Crisis Group report nevertheless found that there was still deep suspicion between the military that some former rebels.