Right-wing Hindu protesters in the Indian city of Mumbai have doused a political activist in black ink to protest at the launch of a book by a former Pakistani foreign minister.

The Shiv Sena party said the ink attack on Sudheendra Kulkarni was a form of "peaceful protest" against Pakistan.

It later cancelled a planned protest at the launch of Khurshid Mahmud Kasuri's new book amid outcry over the incident.

Kulkarni was the main organiser of Kasuri's book launch.

The activist attended several press conferences with the black ink still on his face before being admitted to hospital.

The Shiv Sena is a junior coalition partner in the Maharashtra state government, which is ruled by the BJP.

The party was founded in 1966 to keep South Indian migrants out of Maharashtra state and to halt the spread of Islam.

Over time, it has acquired a reputation of promoting religious and ethnic chauvinism while allegedly targeting minorities, especially Muslims.

"A group of 10 or 15 Shiv Sainiks mobbed me, they stopped my car, asked me to come out, they caught me, started abusing me, they said we had ordered you to stop the launch this evening, you didn't listen to us, this is what we'll do with you," Kulkarni told reporters.

"The ink attack on Kulkarni is a mild reaction from (Shiv) Sena, this is not ink but the blood of our soldiers," party leader Sanjay Raut, told the media shortly after the incident.

Later Raut said the protest had been called off following a conversation with the state's chief minister, Devendra Fadnavis, who had told him that "there should be no anti-Pakistan protest at the event".

Shiv Sena's action drew widespread condemnation, including from senior BJP leader LK Advani.

"This morning I saw on TV my long-time colleague Sudheendra Kulkarni has been attacked. I do not want to name anybody, but such incidents show a growing intolerance towards views that are different from one's own. I strongly condemn the attack," he was quoted as saying by the Indian Express newspaper.

This incident comes amid a series of events that have led to growing concerns about the treatment of minorities in India.

Last month a 50-year-old Muslim man from north Indian was lynched over rumours that he had stored and consumed beef.

The Shiv Sena party also forced the cancellation of a concert by Pakistani singer Ghulam Ali last week.

And last week state lawmakers from the ruling BJP party attacked an independent Muslim politician in Kashmir because he had held a "beef party"