Security aboard Air-India and Indian Airlines flights has been stepped up after intelligence reports last week suggested terrorists might try to hijack an Indian plane flying to or from the Persian Gulf, an airline spokesman said Wednesday.

The state-run carriers were taking numerous anti-hijacking measures, Air-India (search) spokesman Jitender Bhargava said. He declined to give details about who is suspected of planning such an attack.

"The alert was sounded a week ago and it continues," said Bhargava, who was also speaking on behalf of Indian Airlines (search). Both airlines are state-owned. The alert was first reported in newspapers on Wednesday.

Additional security arrangements include frisking passengers and a final check before boarding, Bhargava said.

The warning about a possible hijacking of a Gulf-bound plane was issued by India's Bureau of Civil Aviation Security, the Indian Express Newspaper reported Wednesday, when news of the alert first emerged.

The warning was based on a tip from defense intelligence units, who said it applied specifically to flights to or from Dubai (search) in the United Arab Emirates, the report said.

Officials at New Delhi airport received a telephone call Wednesday warning that a flight to the southern Indian city of Hyderabad later in the day would be hijacked, the Press Trust of India reported, quoting an unidentified police official.

Commandos rushed to the tarmac and began checking flights, but the call turned out to be a hoax, the news agency said.

Air-India and Indian Airlines operate 150 flights a week to various Persian Gulf destinations, including the Emirates, Bahrain and Qatar. Security has been increased on all flights to the Gulf, Bhargava said.

The Indian Express said additional security staff had been hired by both airlines to guard their aircraft at Dubai airport.

Islamic militants hijacked an Indian Airlines jetliner from Katmandu, Nepal, in December 1999. The hijackers flew the plane to Kandahar in then Taliban-ruled Afghanistan, and the aircraft and its passengers were released only after the Indian government freed three Islamic militants held in Indian jails.

Indian airports that have flights landing from Persian Gulf states also have been placed on high alert, the newspaper said. Those include Bombay, New Delhi, Hyderabad, Cochin and Calicut.