Indonesian police have arrested a woman in Sulawesi island for smuggling into the country from Malaysia a large quantity of raw material that can be used for bomb-making.

The woman was arrested on Oct 16 in Parepare town in South Sulawesi province, said national police spokesman Sunarko Danu Ardanto.

She was the fifth person detained in the case.

Three other women and a man have already been arrested for allegedly smuggling hundreds of kilograms of ammonium nitrate from Sabah last week. They were arrested separately in the Indonesian border town of Nunukan in East Kalimantan.

Police seized a total of 389.5 kilograms of ammonium nitrate, 900 detonators and 20 pieces of wire from all five, Ardanto said.

He added that Indonesian detectives are investigating with their Malaysian counterparts and it was yet not determined what the five wanted to do with the materials.

Ammonium nitrate is used in explosives and fertilisers.

Police on alert

Indonesian police have been on alert following the October 1 suicide bombings on the resort island of Bali, which killed 20 people and the three attackers.

Officials have said they suspect Malaysians Noordin Mohammad Top and Azahari Husin, leading members of the Islamic extremist group Jemaah Islamiah (JI), could have masterminded the violence.

An expert on JI has said both men could be creating their own group after splitting from JI's mainstream command structure, which is concerned about heavy Muslim casualties from other bombings.

Authorities believe Noordin and Azahari played key roles in the 2002 Bali blasts which killed 202 people, and in deadly suicide attacks at a Jakarta hotel and the Australian embassy.