The 10 suspected members of Jemaah Islamiyah (JI), a regional terrorist network linked to al-Qaeda, were arrested during various raids since June 28 at several locations in South Sumatra province.

The latest arrest took place on Tuesday in the provincial capital of Palembang, national police spokesman Abubakar Nataprawira told reporters.

While local media earlier named the Singaporean as Alim, alias Omar or Taslim, and was arrested Saturday in South Sumatra district of Sekayu, but Nataprawira identified the Singaporean only with his initial as "MH."

"The suspect gave training in assembling bombs to people in Palembang related to terrorist acts in Indonesia," Nataprawira said, adding that he was associated with Mas Selamat bin Kastari, the alleged leader of Jemaah Islamiyah's Singapore operations who escaped from the city-state's prison earlier this year.

Nine of the 10 unidentified suspects, handcuffed and blindfolded, arrived in Jakarta from Palembang on a police aircraft, witnesses said.

They were escorted by masked and heavily-armed plainclothes anti- terrorist officers to police headquarters outside Jakarta.

In addition to 20 assembled bombs - 16 of them ready to be detonated - the counter-terror units also seized dozens of kilograms of potassium chlorate and other explosive materials as well as several hand grenades, Nataprawira said.

Police believe Singaporean Alim, an Afghanistan-trained bomb- maker, was a close aide to Malaysian master bomb-maker Azahari bin Husin, who was killed in a shootout with police at his East Java provinces hideout in late 2005.

Colonel Karuna Amman returned to Sri Lanka on Thursday. It is not clear whether he was deported or opted for voluntary repatriation after withdrawing an application for asylum.

Amman's breakaway Tamil paramilitary group, the TVMP, which now supports the Colombo government, has been accused of abducting teenagers, forcing them to serve as child soldiers. Karuna entered the UK on a forged diplomatic passport. He was arrested in a police raid in London last summer. During his trial for immigration offences in January it was said that the diplomatic passport and UK visa were supplied to him by Sri Lanka's defence minister. The country's high commission in London denied the allegation.

In response to a freedom of information request by the Guardian the Crown Prosecution Service said that there was no "realistic prospect" of a conviction against Col Karuna "based on the evidence that has been submitted to the CPS". Karuna's wife and children live in the UK.