Elephants are used for religious ceremonies in India

The plan follows concern about the welfare of Mumbai's elephants, which are mainly used in religious functions.

Four elephants are legally registered in Mumbai, but locals believe up to a dozen could be living in the city.

The implants cost 200 rupees ($4.40) and will be ready to be implanted into the animals' ears over the next month.

Faked registrations

Sarfaraz Khan, the deputy conservator of forests for Mumbai's Thane district, told BBC News that illegal elephants had become a problem for locals.

"Some illegal elephants enter the city. They cause some traffic problems and sometimes they scare some people, also they indulge in begging sometimes.

"These people who have them legally do not create as much problems," he said.

Mr Khan said that it was necessary to use the rice grain-sized implants because some elephant owners had been faking their registration certificates by taking photocopies of other owners' licences.

He said similar registration schemes had been trialled on ceremonial animals elsewhere in India.

A 30-year-old elephant was killed by traffic in Mumbai last month

"It has been done earlier on leopards also, not in Mumbai but in Kerala."

The issue has gained prominence in recent weeks after Lakshmi, a 30-year-old elephant used for religious ceremonies, was allegedly struck and killed by a drunk driver.

The incident prompted Bollywood actor Rahul Khanna, a patron of India's branch of People for the Ethical Treatment of Animals (Peta), to call for elephants to be banned from the city.

Religious significance

The proposal was echoed by Suresh Kadam, assistant secretary of the local Society for the Prevention of Cruelty to Animals.

"Mumbai is a commercial place. People are using these elephants for begging purposes. The roadsides are narrow and not sufficient to leave space for the elephant.

"We would like to ban these elephants here so that they can return to their natural environment."

He said that the deaths of elephants in Mumbai were not uncommon. Another elephant had been killed in 2002 after being struck by traffic.

Elephants are popular in India because of their resemblance to the elephant-headed god Ganesh, one of the most prominent deities in the Hindu pantheon.

They are commonly used in processions, and are also hired for weddings, inaugurations and political rallies.

There are no wild elephants in Maharashtra state and most of those found in Mumbai are transported or driven on foot from the forests of Bihar, 1,500km to the northeast.