Two Muslim men suspected of stealing cows have died of injuries sustained after being assaulted by villagers in the northeastern Indian state of Assam, according to local police.

Police said they had registered a murder case over the deaths of Abu Hanifa and Riyazuddin Ali who were beaten with sticks on Sunday. Two suspects have been detained for questioning.

The incident comes amid rising tensions over the killing and smuggling of cows in India, a Hindu-majority country where the animal is considered sacred and its slaughter is a punishable offence in many states.

"They were chased and beaten with sticks by villagers who said the two boys were trying to steal cows from their grazing field," Debaraj Upadhyay, Nagaon district's top police officer, told AFP news agency by telephone.

"By the time we took them to the hospital at night they had succumbed to their injuries."

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Updadhyay dismissed any suggestion that a vigilante group or association was involved in the incident.

There have been a spate of attacks in recent months by so-called cow protection vigilante groups, allied with Narendra Modi's governing BJP, who roam some highways inspecting livestock trucks for any trace of the animal.

Last month a Muslim man carrying cows on a truck with valid papers was attacked by a group in Rajasthan state, which is ruled by the BJP. He died later in hospital while his two sons, who were brutally attacked with him, recovered from their injuries.

The state home minister was criticised for blaming both sides for the incident.

Vigilantes emboldened

In 2015, a Muslim man was lynched by his neighbours over rumours that he had slaughtered a cow. Police later said the meat was goat meat.

Critics say the vigilantes have been emboldened by the election of Narendra Modi as prime minister in 2014, who so far has refused to condemn the deaths of Muslims by vigilante groups.

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Most Indian states have a ban in place on cow slaughter but in recent years, BJP-ruled states have passed stringent legislation, with the western Gujarat state enacting a law that calls for life imprisonment for slaughtering a cow.

In India's most populous state, Uttar Pradesh, where BJP came to power last month, abattoirs have been closed down for flouting licence rules.

Critics say the move is based on religion as Muslims traditionally run the meat business in India