Security has been stepped up at a number of major Indian airports after warnings that a flight to or from Nepal could be hijacked, a security official said on Wednesday.

The alert was issued after a New Delhi court ordered a Kashmiri man to be hanged on October 20 for his role in a 2001 attack on the Indian parliament,.

Mohammed Afzal's wife on Tuesday asked the president of India, A.P.J. Abdul Kalam, to pardon her husband, and his decision is awaited.

"We have received a specific intelligence input that terrorists may plan to hijack a plane to or from Kathmandu in response to the hanging," the official, who asked not to be named said.

In response to the threat, more security officials have been sent to at least 13 airports, manual searches have been increased and quick-reaction teams stationed at airports have been told to be extra vigilant.

Since the hanging date was announced last week, there have been nearly daily protests in Indian Kashmir.

The airports include those in the capital, New Delhi, and the cities of Lucknow, Patna, Varanasi and Kolkata.

Five gunmen stormed the heavily guarded parliament complex on December 13, 2001. The attack, blamed by India on Pakistan but denied by Islamabad, brought the nuclear-armed rivals dangerously close to their fourth war.

More than 45,000 people have been killed in the 17-year-old separatist revolt in Jammu and Kashmir.

An Indian Airlines plane was hijacked by Kashmiri militants in 1999 en route from Kathmandu to New Delhi and was taken to the Afghan city of Kandahar.

The week-long siege ended after India released three Kashmiri militants from prison.