A Hindu cow rights activist who drank pesticide as part of a protest in India calling for the animals to be given greater protection has died of his injuries.

Key points: Protesters were demonstrating against what they say is the ongoing slaughter of cows

Protesters were demonstrating against what they say is the ongoing slaughter of cows Police do not believe the man intended to take his own life

Police do not believe the man intended to take his own life About 27 members of the same group also tried to block roads

The 40-year-old man was one of eight "gau bhakt", or cow worshippers, who consumed the poison at a rally outside a government office in western Gujarat state on Thursday.

They were protesting at what they say is the ongoing slaughter of cows, considered sacred by India's large Hindu population, despite a widespread ban on killing the animals.

"These men had come with bottles of poisonous substance and consumed a small portion in front of the collectors office," Manish Nakum, a police inspector investigating the case, said.

"All were rushed to the government hospital where one of them, identified as Gabhru Bharwad, 40, died during treatment in the evening."

Inspector Nakum said he did not believe the men, who drank a mild pesticide used on cotton plants, intended to take his own life.

Four of the protesters, aged in their 20s and 30s, were moved to a private hospital after their condition deteriorated, police said.

Attacks on secular intellectuals, Muslims suspected of killing cows

Cow slaughter and the consumption of beef are banned in Gujarat and several other states in officially secular India.

But the activists claim cows are still being killed illegally and want cows to be given the special status of "rashtra mata", or "mother of the nation".

Dhaval Pandya, who participated in the protest in Rajkot city but did not drink pesticide, told reporters that cow slaughter was rampant in India.

"So to protect cows, which are holy to us like gods, we need to declare it as the mother of the nation," he said.

About 27 members of the same group also tried to block roads in Rajkot, but were detained, police said.

Around 80 per cent of India's 1.2 billion population is Hindu, but it is also home to large numbers of Muslims, Christians and Buddhists.

A spate of attacks on secular intellectuals and Muslims suspected of killing cows have heightened concerns of mounting intolerance under rightwing nationalist Prime Minister Narendra Modi's two-year-old government.

AFP