CHENNAI, India - Police in southern India have launched a hotline to prevent "honor killings", the first initiative of its kind in the country aimed at protecting couples from different castes or religions who fear family retribution.

The toll-free number is linked to an immediate response team who will take action in cases where couples feel threatened by their families, police said.

"It will operate 24/7 and we have come up with standard procedures that will be used in every case," said Mahesh Kumar Aggarwal, police commissioner of Madurai in Tamil Nadu state.

"The couple will be provided protection."

Nearly 400 people - mostly women - have died in honor killings in India since 2014, according to government data. The killings are usually carried out by family members who believe the relationship has brought "shame" on their community.

But activists say the crime is under-reported and many killings are covered up and made to look like suicides by hanging or consuming poison.

Despite India's growing cosmopolitanism, the intermingling of different castes or religions remains a taboo in Indian marriages - not only among rural populations, but even for well-off urban families.

The Madurai police initiative follows a Madras High Court order last year that called for specialist police units to be set up to deal with complaints from "couples expressing fear of physical annihilation" by parents, relatives and khaps panchayats - community groups made up of powerful men who set the rules in villages.

The court recommended that temporary shelter be provided by the state to couples who felt at risk, and counselling offered to family members opposing the marriage.

It made the order after hearing the case of a man who fell in love with and married a girl from a higher caste in 2014. Both had been hounded and the girl was later killed.

There were 47 reported cases of honor killings between 2010 and 2015 in Tamil Nadu, according to court papers.

"This (helpline) is a positive development," said K. Samuelraj, an activist from a group campaigning against honor killings in the state.

"But such toll-free numbers have to be set up across the state. We are pushing for the setting up of special units in every district to ensure couples are safe. Many still live in fear."

Reuters