Indonesia detains four soldiers over acid attack on activist

Indonesian authorities have detained four soldiers for their alleged role in an acid attack on an activist who criticised the military's influence in government, officials said.

Andrie Yunus from KontraS, a prominent rights group that investigates forced disappearances, suffered burns to more than 20% of his body after two men on a scooter splashed him with acid last week.

The UN High Commissioner for Human Rights, Volker Turk, said he was "deeply concerned" with the attack while KontraS said it was an "attempt to silence critical voices".

The motive for the attack is being investigated, military police commander Yusri Nuryanto said. The four soldiers are from the intelligence unit, he added.

Andrie was taken to a hospital in Jakarta after the attack, where an examination revealed burns to parts of his body, including his hands, face, chest and eyes, KontraS said in a statement.

He was riding his motorcycle at the time after recording a podcast about the military's growing role in politics, the group said.

The acid attack unleashed a new wave of concern. Over the weekend, protesters gathered in parts of the country to show their support.

Rights advocates have also urged Indonesian president Prabowo Subianto, a retired general, to form an independent team to investigate the case.

While Prabowo has not publicly addressed these calls, a presidental spokesperson said on Tuesday that he has ordered an "objective, open and expeditious investigation".

Andrie is a vocal critic of a controversial revision to Indonesia's military law, which would expand the roles of military officers in government. The bill was passed last year.

In recent months, he had investigated the authorities' handling of violent anti-government protests last year, said the Civil Society Coalition, an umbrella organisation of human rights groups.

Andrie had received "various forms of intimidation" including calls from unknown numbers, in the days leading up to the acid attack, the coalition said.

Activists in Indonesia have long flagged concerns about being intimidated for their advocacy work.

In January, rights campaigners said some activists received threats, including chicken carcasses and at least one Molotov cocktail, for their criticism of the government's flood response.