TARANAGAR: As a truck screeches to a halt on an Indian highway in the middle of the night, devout young Hindus armed with sticks scramble inside, searching for cows they consider sacred.

Almost every night, the vigilantes lie in wait for suspected cattle smugglers in the desert state of Rajasthan, ready to fight to protect the animals, a revered symbol of India's majority Hindu religion.

"Smugglers often open fire or try to run us over. I even get death threats but nothing bothers me," said Babulal Jangir, a leader of the Gau Raksha Dal (Cow Protection Squad).

"My heart beats only for my dear cow mother."

Cow slaughter and consumption of beef are banned in Rajasthan and many other states of officially secular India, which has substantial Muslim and Christian populations.

But the recent killing of at least three Muslims suspected of eating beef or smuggling cows by Hindu mobs have heightened fears of rising violence against India's religious minorities.

The deaths have also sparked a wider debate about growing religious intolerance since Indian Prime Minister Narendra Modi's Hindu nationalist government came to power at general elections last May.

Dozens of authors have returned India's highest literary award in protest over the rise in violence, which they fear includes the recent murder of a secular intellectual, while petitions demanding government action have attracted signature from scientists, actors and filmmakers.

The government has been accused of failing to rein in Hindu hardliners, while its ministers have at times appeared to be inflaming the debate.

Modi's Bharatiya Janata Party (BJP) suffered a crushing blow in a weekend state election, in part, analysts say, because of its attempts to polarise voters along religious lines.

Beaten to death

In September, a Muslim family was attacked outside Delhi by a group of Hindus after false rumours they were keeping beef in their home.

The father was beaten to death and his son was severely injured.

Several other incidents were reported weeks later, including the killing of a truck driver in northern Himachal Pradesh state for attempting to smuggle cattle to a slaughter house.

Critics say Hindu hardliners and their radical elements have become more emboldened since Modi's landslide victory last year.

Jangir said his squad has grown to some 20,000 members, ranging from farmers to lawyers and teachers, along with a fast growing network of informers prowling Rajasthan's major roads.

"It is extremely disturbing when ordinary people take the law into their hands," said Zafarul Islam Khan, president of the All India Muslim Majlis-e-Mushawarat, a leading Muslim body.

"They right-wing groups have their goons going around saying 'We will dispense justice, there is no need for courts'. What is really sad is that they seem to enjoy police and political patronage," he said.

But Jangir, who runs a furniture business, has no sympathy for beef eaters and his team have no qualms about dispensing "rough justice", usually in the form of beatings.

"Anyone who eats cow meat should be handed the death sentence," the 42-year-old said, adjusting buckles on his bullet-proof vest.

On the night an AFP team joined one of their patrols, the mob became heated when cows were found inside a stopped truck.

The anxious driver was finally allowed to proceed when he produced documents showing the cows were headed for a dairy, not an illegal slaughter house or across the border to Bangladesh where beef is in high demand.

"Our Hindu scriptures say 330 million gods and goddesses reside in one cow," said Manoj Jangir, another squad member, who has a degree in political administration.

'Our blood starts boiling'

The BJP has rejected the violence and denies local media reports the Modi government is moving to introduce a nationwide ban on cow slaughter.

"No one can indulge in any kind of violence. We don't support these groups," GVL Narsimha Rao, a BJP spokesman, told AFP.

In southern Kerala and the remote northeast — areas with large Christian populations — beef is legally and widely consumed.

But in Rajasthan and other states, eating, killing or selling cows is a non-bailable offence, though the consumption of buffalos is allowed as they are less revered.

In western Maharashtra, offenders can be jailed for up to five years.

Still, an illegal trade thrives in trucking cows across the country into Muslim-majority Bangladesh.

"It is a kind of do or die thing for us. When we see how cows are stuffed inside trucks our blood starts boiling," said Maniram Babu, 31, a mechanic and squad member.

"We get very emotional and then we can't stop ourselves from teaching the smugglers a lesson or two."