Less than a week after the suicide-truck attack against the Marriott Hotel in the capital city, Islamabad International Airport's passenger lounges and parking areas were evacuated today after a suicide terrorism threat was phoned in to an airport official in the southern port city of Karachi.

The caller threatened various airports throughout the country and said attacks would occur by 12:40 p.m, reports [1] the Press Trust of India.

Islamabad International Airport's threat level was raised from "high alert" to "red alert."

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"We put the airport on red alert and allowed only passengers and no visitors," said Colonel Ashraf Faiz, chief airport security officer. "The parking (of vehicles) has been stopped."

Flight schedules were not interrupted, said the airport's manager Ayaz Jadoon.

The deadline for attack, however, passed without incident.  Nevertheless, the airport will remain on red alert, the Guardian reports [3]. Islamabad, and Pakistan more generally, is still reeling from the suicide attack against the Marriott Hotel on Saturday evening that killed 53 people.

Islamabad's International Airport has been the scene of a suicide attack before. In February 2007, a suicide bomber opened fire near the VIP area of the airport before detonating a hand grenade. Three people were injured in the attack, according to the Press Trust of India.