Indian police said on Sunday they have arrested 32 people after a man was killed by a mob in the country's latest lynching over suspicion of child kidnapping sparked by rumours on WhatsApp.

The men were arrested over the murder of Google employee Mohammad Azam who was attacked along with two friends by a 2,000-strong mob in southern Karnataka state's Bidar district late on Friday.

Azam's friends, including a Qatar national, were critically injured in the assault that came days after the Facebook-owned messaging service published advertisements in Indian newspapers offering tips to curb the spread of fake information on its platform.

More than 20 people have been lynched in India after being accused of child abduction in the last two months.

Police said 27-year-old Azam and his companions were returning to their home in neighbouring Hyderabad city after visiting a friend in Bidar when they stopped midway and offered chocolates to local school children.

“One of them had bought chocolates from Qatar and tried to offer it to the children as a token of affection,” Bidar deputy police chief V N Patil told AFP.

But one of the children started crying, alerting the elders who accused the men of being child kidnappers amid rife social media rumours about child kidnapping rings in the area, the officer said.

Patil said the three managed to flee but were attacked by a much larger mob a few kilometres (miles) ahead after locals alerted nearby villages via Whatsapp.

Their car flipped after hitting a roadblock placed by the angry mob before they were dragged out of the vehicle and beaten with sticks and stones.

Rampage

A video broadcast on Indian news channels showed a policeman pleading with the attackers as they kicked and hit the victims with sticks.

Three policemen were injured in rescue attempts as the mob rampaged for nearly an hour.

Police said they have arrested 32 attackers and a manhunt is on for others.

Some of the accused were identified from the attack video circulating on WhatsApp.

An investigating officer speaking on condition of anonymity told AFP that those arrested included the administrator of a WhatsApp group behind the viral message that triggered the attack.

The latest attack comes after five people were lynched by a mob in neighbouring Maharashtra state on July 1.

The mob had spotted the victims talking to a child at a market, triggering allegations of child abduction.

Azam's brother Ahmad told reporters in Hyderabad that his brother and his friends were returning in a brand new car when they were chased by the mob and beaten ruthlessly.

“It's just shocking. The mob was so violent that they refused to budge even after one of my brother's friends showed his Qatari passport,” Ahmad said, urging the government to take tough action against rumours spreading on WhatsApp.

The spate of lynchings started last May in eastern Jharkhand state after rumours on WhatsApp about child kidnappers led to the killing of seven men.

The rumours have since resurfaced, with 21 deaths reported in dozens of attacks across the country mostly targeting non-locals.

India accused WhatsApp of failing to curb false information on its platform.

WhatsApp has promised to introduce new features to flag forwarded messages but has refused to snoop on user content over privacy protection.

India is WhatsApp's largest market in the world, with some 200 million users sending a billion messages each day.