India's highest court has ruled that having sexual intercourse with a wife under the age of 18 is rape.

Activists hailed the decision as an important step towards ending child marriages.

Indian law has set 18 as the age for women to marry and consent to sex, but there are exceptions and a man was permitted to have sex, even forcibly, with a girl as young as 15, as long as she was his wife.

The Supreme Court in New Delhi ruled on Wednesday that sexual intercourse with a girl younger than 18 is rape.

Lawyer Indira Jaisingh said the ruling would make child marriages illegal.

Child marriages are prevalent in India, especially among the rural poor.