A Singapore rapper who has accused authorities of racism was handed a six-week jail term on Tuesday over his social media posts including a video criticising an actor in brownface and comments alleging unequal treatment of the city's races.

Subhas Nair, an outspoken musician of Indian descent, was found guilty of attempting to promote ill will between different ethnic and religious groups.

Singapore's government has long sought to promote racial harmony among its diverse population of 5.6 million, but some still complain that the ethnic Chinese majority enjoy greater privileges.

Nair was found guilty of four counts of attempting to promote ill will among racial and religious groups earlier this year.

One of the charges related to a 2019 rap video that criticised an advert featuring a local Chinese actor who darkened his skin to portray an Indian.

During his trial, Nair testified that the video was intended to end such instances of "brownface" in Singapore.

"Subhas has filed an appeal against both his guilty verdict, as well as his sentence," his lawyer Suang Wijaya told AFP.

Nair has been granted bail pending appeal, he added.

Police in 2019 issued a warning over the video to Nair and his sister Preetipls -- a well-known local comedian, who rapped alongside him.

Nair was charged after he reoffended by posting comments on social media over the next two years, including a post appearing to suggest a Chinese man involved in the death of an Indian received lenient treatment from authorities because of his race.

Police previously called the allegations "baseless" and said they "have the potential to damage religious and racial harmony in Singapore".

Singapore, home to Muslim Malay and ethnic Indian minorities alongside the ethnic Chinese majority, has strict laws against sowing racial and religious tensions.

Anyone found guilty of attempting to promote ill will between different religious or racial groups can be jailed for up to three years, fined, or both.