SINGAPORE - Police are investigating protests held in several locations in Singapore in support of farmers in India.

Images of the protests, allegedly held without a police permit, were posted on social media but have subsequently been taken down.

In a statement on Tuesday (Dec 15), the police said organising or taking part in a public assembly without a police permit is illegal and an offence under the Public Order Act.

They further said they will not grant a permit for any assembly that advocates political causes of other countries.

"Foreigners visiting or living in Singapore should abide by our laws," said the police. "Those who break the law will be dealt with firmly, and this may include termination of visa or work passes, where applicable."

Farmers in Northern India have been protesting against Indian Prime Minister Narendra Modi's decision in September to remove the system of government-run purchase of crops in a wholesale market, which had ensured a minimum price for their produce.

They say the move will hurt their livelihood, and have turned down proposals for discussions with the government.

Protesters have blockaded roads and the police have occasionally used tear gas to disperse them.

The protests have made waves on social media that are rippling beyond India's borders to countries with significant Indian diaspora communities.

On Monday, Al Jazeera reported that British Punjabis were protesting in London in solidarity with those farmers in their ancestral home in Punjab, a Northern Indian state described as the "bread basket of India".

The online report said: "Earlier this month, thousands of British Punjabis gathered outside the High Commission of India in central London, in support of the striking farmers, or 'kisaan' as they are known in Punjabi."