The authorities in Indonesia's Aceh province have ruled out pursuing espionage charges against a Scottish woman detained for the past month, the prosecutor handling their case said.

"According to the chief, if we focus on spying it will be difficult to prove in court later," prosecutor Zainal Said told AFP Thursday.

Last Saturday Said said there were indications of espionage in the activities of Lesley McCulloch, who has been detained along with her American travelling companion Joy Ernestine-Sadler, since September 11.

On October 3, Said assigned a team of three prosecutors to examine the case file which police had prepared against the women. After their review and consultation with Aceh's top prosecutor they have decided to focus their case on the women's alleged visa misuse, Said said.

The prosecution team decided the case file was not complete and within two days will send it back to police for further investigation, Said said.

Ernestine-Sadler's case had always been based on alleged visa misuse, Said said, but the case file against McCulloch was filled with alleged notes she made showing "state secrets", specifically the strength and movement of Indonesian security forces.

It also contained copies of newspaper articles by McCulloch, photographs of victims of violence, and photographs of McCulloch with guerrilla leaders of the Free Aceh Movement (GAM) rebels who have been fighting for an independent state since 1976. The evidence came from McCulloch's own laptop computer, Said said on Saturday.

McCulloch was until recently a university lecturer in Tasmania, Australia, and is a frequent contributor on the Aceh dispute to Asian newspapers.

In one of several letters recently smuggled out of her detention room at Aceh police headquarters, she wrote that "the Indonesian military and police have a deep-seated hatred of my work." McCulloch and Ernestine-Sadler were detained along with their local translator when security forces stopped them in South Aceh district. The translator is being treated as a witness in the case.

Authorities allege McCulloch conducted research and Ernestine-Sadler engaged in humanitarian activities not in keeping with their tourist visas. Their lawyer has said they deny misusing their visas.

An estimated 10,000 people have died since the Aceh conflict began in the energy-rich province on Sumatra island, with rights activists putting the toll for this year alone at around 1,000.