It was triggered after an Indian construction worker was fatally hit by a bus in a district known as Little India, where tens of thousands of South Asian labourers converge on weekends.

In a statement on Friday evening, police commissioner Ng Joo Hee said the 53 men originally slated for deportation had already been sent to their home countries after receiving police warnings and immigration removal orders.

Four other Indian nationals who were released on Tuesday after criminal charges were withdrawn will also be repatriated on Friday after being served with police warnings, Ng said.

No reasons were given for the decision to deport the four additional men after their release from police custody.

“When the last of these four are removed, bringing the total number repatriated to 57, the repatriation operation arising from police investigations into the Little India riots will, more or less, come to an end,” Ng said.

The Ministry of Home Affairs had earlier stated that the men being deported were deemed to have threatened public order for failing to disperse despite police orders.

The 28 Indian nationals currently remanded in police custody and facing rioting charges were judged to have been active participants in the riot.

About 200 others will be handed “police advisories” after investigations showed they were at the scene of the riot but were “relatively passive”.

The mass repatriation comes as international rights groups including Humans Rights Watch and Amnesty International accused the government this week of arbitrarily deporting people without due process, in its haste to punish the alleged rioters.

The government maintains that it has legal powers to repatriate foreigners deemed a threat to public security.

In December last year, 29 Chinese bus drivers were deported for their involvement in a work stoppage for better wages and living conditions – the first industrial strike in the city-state since 1986.

Five others served jail terms after the strike was declared illegal.