India could issue millions of cows with unique identification numbers, the latest effort to protect the sacred animals amid a spike in violence by Hindu vigilantes against farmers accused of cattle smuggling.

The Indian government has told the country's top court that millions of cows will be tagged with a tamper-proof plastic tag linked to a national database in a bid to curb smuggling within the country and beyond its borders.

Cows are considered sacred in Hindu-majority India, and their slaughter is a punishable offence in many states.

“Each animal will have a unique number that will have details like age, breed, sex, height, colour, horn type and special marks,” a senior officer from India's home ministry that prepared the recommendations told AFP.

A panel from the home ministry was tasked by Prime Minister Narendra Modi's right-wing government to propose measures against cross-border smuggling after a petition was filed by an animal rights group in the court.

Nearly 175,000 cattle are seized annually on the largely porous borders with Bangladesh and Nepal, according to home ministry figures, with unofficial estimates of the illegal cow trade pegged at nearly two million animals.

The proposal comes amid a spike in violence by Hindu mobs against farmers transporting livestock, and a broader crackdown on butchers in India's most populous state Uttar Pradesh.

Vigilante squads roaming highways checking livestock trucks for the sacred animals have proliferated since the Hindu nationalist Bharatiya Janata Party (BJP) came to power in 2014.

These so-called “cow protection squads” beat a Muslim man to death on a highway in Rajasthan this month, accusing him of secretly taking cattle to an abattoir for illegal slaughter. The man was a dairy farmer transporting milk cows.

Three men transporting buffaloes in their truck were beaten this week in the capital New Delhi. At least 10 Muslim men have been killed in similar incidents across the country by Hindu mobs on suspicion of eating beef or smuggling cows in the last two years.

Most Indian states have banned cow slaughter and imposed heavy penalties and jail terms on offenders, while the transportation of cattle across state lines is also barred in several jurisdictions.