SINGAPORE - The police are looking into an alleged protest on an MRT train on Saturday (June 3).

This follows a police report which was lodged after a group was seen protesting against the detentions under the Internal Security Act (ISA) 30 years ago.

In 1987, 22 activists were arrested under Operation Spectrum for being part of what the Government called a Marxist plot aimed at overthrowing it.

The protest comes after some former ISA detainees launched a book in May titled 1987: Singapore's Marxist Conspiracy 30 years On.

A group of about seven people were seen riding a train on the North-South Line while holding copies of the book and wearing blindfolds in a silent protest. Social activist Jolovan Wham had posted pictures of it on Facebook on Saturday.

The Straits Times understands that the police report was made on Sunday.

A police spokesman said that anyone with information on the incident can submit it to www.police.gov.sg/iwitness and all information will be kept strictly confidential.