SINGAPORE - A 32-year-old Indian national is being investigated for participating in a public assembly without a police permit, the police said on Wednesday (Dec 25).

He had allegedly committed the offence at Marina Bay, to protest against India's Citizenship (Amendment) Act.

The Straits Times understands that the man had posted a picture of himself on social media, holding a placard to express his unhappiness.

His occupation and residence status in Singapore are currently unclear.

It is believed that more than one person could be investigated in the case.

In a statement, the police said that organising or participating in a public assembly without a police permit is illegal and an offence under the Public Order Act.

"The police will not grant any permit for assemblies that advocate political causes of other countries. Foreigners visiting or living in Singapore should abide by our laws," the statement said.

Street protests have erupted in at least 25 cities across India since the government there passed the Citizenship (Amendment) Act last week.

The change, which some say threatens to erode India's secular foundation, seeks to provide citizenship to non-Muslim illegal immigrants from Afghanistan, Pakistan and Bangladesh.