While they escaped being charged in court, there was still enough evidence against a group of 53 foreign workers to repatriate them for their involvement in the Little India riot on Dec 8.
The 52 Indian nationals and a Bangladeshi were picked up by police in an islandwide operation on Dec 17.
At a press conference held at the police headquarters in Novena on Dec 17, Deputy Prime Minister Teo Chee Hean said: "They had knowingly joined or continued to participate in the riot after being ordered to disperse, impeding riot control and emergency rescue operations."
Mr Teo, who is also Minister for Home Affairs, added: "Basically, we have the laws in order for a person to be assessed as having posed a threat to our safety and security.
And these persons, by their actions... satisfied those conditions."
The men are being held in a prison in Admiralty West, and will be given time to secure their final salaries, close their bank accounts, and finish up any other administrative work.
The 53 were hired by 48 different companies, and had mostly worked here for less than five years. Half of them were from the building and construction sector, said Commissioner of Police Ng Joo Hee.
They will be prohibited from returning to Singapore.