NEW DELHI — India's Supreme Court on Tuesday told state governments to "ruthlessly" stamp out so-called honour killings and warned that officials who fail to deal with the practice would be prosecuted.

India has seen a recent upsurge in such crimes, which mainly involve young couples who marry outside their caste and are murdered by relatives to protect what they see as the family's reputation and pride.

The court on Tuesday lashed out at councils of village elders, known locally as khap panchayats, as "kangaroo courts," saying they encouraged honour killings.

"There is nothing honourable in honour killing or other atrocities and, in fact, it is nothing but barbaric and shameful murder," judges Markandeya Katju and Gyan Sudha Mishra said in the judgment.

"We have heard of khap panchayats which often decree or encourage honour killings or other atrocities in an institutionalised way on boys and girls of different castes and religion, who wish to get married or have been married, or interfere with the personal lives of people," they said.

"We are of the opinion that this is wholly illegal and has to be ruthlessly stamped out."

There are no official figures on honour killings, though an independent study last year suggested that as many as 900 were being committed every year in the northern states of Haryana, Punjab and Uttar Pradesh.

Many go unreported, with police and local politicians turning a blind eye to what some see as an acceptable form of traditional justice.

The court ordered state governments to punish local administrators and police chiefs if they did not respond to honour killings.

Last August Home Minister P. Chidambaram said he would present a bill in parliament which will provide specific, severe penalties to curb such killings.