NEW DELHI:  Indian police have detained four members of a hardline Hindu militia founded by the chief minister of Uttar Pradesh on suspicion of killing a Muslim man who had helped an interfaith couple elope, an investigating official said on Wednesday.

A 60-year-old farmer was killed on Tuesday by a mob that included members of the Hindu Yuva Vahini, or Hindu Youth Force, set up by Yogi Adityanath, a priest recently named by Prime Minister Narendra Modi to lead India's most populous state.

Adityanath, backed by his volunteer force, spearheaded the campaign of Modi's Bharatiya Janta Party (BJP) in this year's Uttar Pradesh state polls, helping to secure a landslide victory in the northern state.

Since his appointment, units of the Hindu Yuva Vahini have ramped up their anti-Muslim rhetoric and launched a campaign against so-called "Love Jihad" - what they regard as an Islamist strategy to convert Hindu women through seduction and marriage.

"The case of a Hindu girl eloping with a Muslim boy led to religious tension and members of the Hindu Yuva Vahini declared it was Love Jihad," said Jagdish Sharma, a police officer leading investigations in Bulandshahr district, 70 km (40 miles) to the southeast of India's capital New Delhi.

"The Muslim farmer was beaten to death in a mango orchard after he refused to share the whereabouts of the couple," said Sharma.

The spokesman of the Hindu Yuva Vahini, P.K. Mall, denied that any members of Adityanath's youth force had been involved in the attack.

"We don't want Muslims to convert Hindu girls but we are not involved in any criminal activity," he told Reuters. "There is a clear conspiracy to insult Yogi Adityanath and our religious group."

Adityanath, who heads a Hindu sect based in eastern Uttar Pradesh, has a history of rabble-rousing street politics, and his sudden rise to political prominence has stoked tensions with Muslims who make up 19 percent of Uttar Pradesh's 220 million people.

Since his appointment, members of the Hindu Yuva Vahini have called on police to enforce a ban imposed by Adityanath on illegal slaughterhouses and taken action to halt sales of meat from unlicensed butchers' shops run by Muslims.

Adityanath, according to Indian media reports last weekend, urged members of the group "behave with decency".