The red alert put on the airports in the provincial capital Quetta and Gwadar indicates a high risk of terror attacks, a security source said.

The alert was raised to "red" after last week's terrorist attack on an army training camp in Dargai which left 42 soldiers dead, sending a wave of panic throughout the country.

A senior official of the Airport Security Force (ASF) said the "high vigilance" level was between the levels of "red and high alert".

Because of the state of "high vigilance", all passes have been canceled and security checks have been strengthened at all airports, including the Islamabad International Airport.

Vehicles entering the airport's premises are being screened by security personnel and passengers and other people are being closely watched.

The high alert was announced by the federal government following reports that five terrorists considered to be accomplices of the Dargai suicide bomber, were out to strike " somewhere in the country."