Three rounds of firing were heard at New Delhi's international airport early Friday morning, but no one was injured, the Indian NDTV channel reported.

Police official said security forces have swarmed through airport after the firing was heard, but no one was injured, said the report.

The channel said security forces were investigating the nature of the incident, which sparked security scare at the airport.

BBC website earlier cited airport officials as saying that at least six gunmen were shot by Indian security force at the airport, but a later report said police had denied any casualties.

NDTV cited the police as saying that the firing was found from a man in a car. The car which has been driven away is being traced by the police.

Airports in India went on high alert on Thursday after the Bureau of Civil Aviation issued a hijack warning.

The move followed an anonymous mail sent to a news organization in Indian western state Gujarat last week, warning of terror strikes at three airports of Delhi, Chennai and Bangalore on the 6th of December.

India's Central Industrial Security Force (CISF) and the National Security Guards (NSG) have been alerted after the warning was released.

(Xinhua News Agency December 5, 2008)