NEW DELHI (Web Desk) - An Indian student was hacked to death and his wife critically injured in southern India in a suspected "honour killing" by relatives angered by their marriage.

The couple married some eight months ago and the woman's family was unhappy as the 22-year-old student, from the lowest Dalit caste, and his wife, who is from a higher caste.

According to police , the 19-year-old woman's relatives were angered by the couple's marriage.

At least three men with sickles and sharp weapons attacked, on a crowded street in Tamil Nadu state on Sunday, police officials said.

CCTV footage of the incident broadcast on Indian television showed the couple walking along the street when three men on a motorbike stop and attack them.

Thevars are a dominant community in Tamil Nadu while Dalits, formerly known as untouchables, are a historically marginalised community.

India has long witnessed so-called honour killings, where couples are targeted because their families or communities disapprove of their relationships over caste or religion. Most occur in rural pockets of the north.