Security was tightened and a red alert declared in Islamabad on Friday following an intelligence tip-off that four suicide bombers might try to penetrate the Pakistani capital and carry out attacks with the help of a local person.

The suspects, identified as Noor Mohammad, Arungzaib, Sher Gul and Hashim belonging to a banned militant group, are planning to enter Islamabad to carry out the attacks, media reports quoted police officials as saying.

The four terrorists will enjoy the support of a local, Sher Mohammad, and stay with him. Intelligence and law-enforcement agencies have started checking hotels in the twin cities for the presence of any suspects, they said.

The foreign office has asked diplomats and foreigners to restrict their moments till further announcement, local daily Dawn reported.

Officials of the Indian High Commission in Islamabad said no such information had been conveyed to them yet. Heavily armed police were seen deployed in many parts of the city, which has already experienced two suicide attacks, one on January 26 at Marriot Hotel and later on the airport on February six.

Security around important buildings, government offices, shopping centres has already been tightened, and hospitals alerted, police said, adding that security around the diplomatic enclave has been further tightened and personnel of the frontier constabulary and elite force have been deployed there.

Islamabad and Punjab police have established pickets at all main roads in the capital as well as exit and entry points, and vehicle were being checked strictly, police said.