India is looking into the possibility that one of the planners of last week's deadly terrorist attacks in Mumbai has been in police custody for months.

Police officials in Uttar Pradesh say a man arrested in February in connection with an attack on a police camp in the city of Rampur had been carrying detailed drawings of hotels, the train terminal and other sites targeted in the attack.

They say the suspect - an Indian national named Faheem Ansari - was also carrying sketches of other sites in Mumbai, including the stock exchange.

Indian officials say Ansari has confessed to being a member of Laskhar-e-Taiba, the Pakistan-based militant group India blames for the attacks. They say he was trained at the same facility as the lone, surviving attacker.

Meanwhile, Indian airports are on high alert Friday, after new threats of possible airborne terror attacks like those against the United States on September 11, 2001.

Airports in New Delhi, Bangalore and Chennai are on "red alert" after receiving warnings of imminent attacks. India's air chief marshal Fali Homi Major says security has been bolstered at airports across the country.

The e-mailed threats claim to come from the Deccan Mujahideen, the same group that took responsibility for terror attacks in Mumbai last week, killing more than 170 people. The e-mails were sent to government officials and media organizations, including VOA.

Hours later, there was a security scare at the New Delhi international airport. Police say they investigated after reports of shots being fired, but found nothing and no one was hurt.

Some information for this report was provided by AP.