Indonesia has detained a British woman named on a list of global terror suspects and plans to deport her for visa violations, authorities told AFP Tuesday.

Tazneen Miriam Sailar -- a Manchester-born convert to Islam married to an Indonesian jihadist who was killed in Syria -- is not charged with terror offences.

But she and her late husband are on an Indonesian police list of suspected extremists that includes several foreigners notorious in the West.

Sailar, 47, and her 10-year-old Indonesia-born son, were being held in Jakarta after being picked up last year without documents allowing her to remain in the Southeast Asian nation, her lawyer Farid Ghozali said.

"She was put (in detention) while awaiting her return, which will be facilitated by the British embassy," Indonesian immigration directorate spokesman Ahmad Nursaleh told AFP.

The embassy declined to comment, and it was unclear when she might be deported.

The police docket does not specify why Sailar was named with some 400 other terror suspects -- including her husband -- on the Indonesian list.

He was killed in Syria in 2015.

The couple's 2010 marriage was officiated by radical Indonesian cleric Abu Bakar Bashir, the spiritual head of extremist group Jemaah Islamiyah (JI), according to sources familiar with the case.

JI members were behind the 2002 Bali bombings which killed more than 200 people -- including nearly 90 Australian holidaymakers -- at two packed bars on the Indonesian island.

Indonesian cleric Abu Bakar Bashir reportedly officiated at Tazneen Miriam Sailar's wedding
Indonesian cleric Abu Bakar Bashir reportedly officiated at Tazneen Miriam Sailar's wedding AFP / STR

Sailar operated a charity named after her late husband, which sent aid to women and children in conflict-wracked Syria, sources said.

She arrived in Muslim-majority Indonesia in 2005 as a medical volunteer for a Christian humanitarian foundation that assisted victims of natural disasters, lawyer Ghozali and a source said.

Jakarta-based security analyst Sidney Jones said Sailar's appearance on the list could restrict her ability to travel and work.

"If you're on this list, it will loom over your head," Jones said.

"For this woman, I don't know what will happen to her if she goes back to the UK."

Several alleged members of the Taliban and IS appear on the Indonesian police list, as well as radical British Islamist Anjem Choudary and Sally-Anne Jones, a recruiter reportedly killed in a US drone strike in Syria.

Maxime Hauchard, a French convert linked to a gruesome IS beheading, and countryman Peter Cherif, a close associate of the siblings who killed staff at Charlie Hebdo magazine in 2015, are also on it.

Sailar was born in Manchester on February 20, 1973, and holds a British passport, according to the list, which also said she goes by at least two aliases.

Indonesian investigators questioned Sailar but no charges were filed, her lawyer said.

"So we're now focused on immigration matters," he said, adding that Sailar wants to remain in Indonesia.