(BSS/AFP) - At least 20 people were missing after violent protests sparked in Indonesia by lavish perks for lawmakers that have come to include anger against police, a rights group said Tuesday.

At least six people have been killed since protests erupted last week, intensified by footage spreading of the killing of a young delivery driver by a paramilitary police unit.

"Based on public reports submitted to KontraS... as of September 1, there were 23 reports of missing persons. After the search and verification process, 20 missing persons remain unfound," the Commission for the Disappeared and Victims of Violence (KontraS) said in a statement.

The group said the 20 were reported missing in the cities of Bandung, Depok and the administrative cities of Central Jakarta, East Jakarta and North Jakarta that make up the wider capital city, with one incident taking place in an "unknown location".

On Monday the United Nations called for an investigation into alleged use of disproportionate force in the protests.

The unrest emerged in cities across the country forcing President Prabowo Subianto into a U-turn on lawmaker perks.

They were the worst protests since the ex-general took power 10 months ago.

On Monday the military was deployed across capital Jakarta as hundreds gathered again outside parliament and clashes were reported in several other cities.