International airports in all major cities of Pakistan were put on alert on Thursday following threats of suicide bombings by Islamic militants, officials and media reports said.
A state of emergency was declared at Islamabad airport, which was recently named after slain former prime minister Benazir Bhutto, after a warning that a suicide bomber could strike the facility located just outside the capital city, reported dpa.
"There is no suicide bomber inside the airport but a threat still exits," top civilian security official Rehman Malik was quoted as saying by the English-language DawnNews television channel.
Malik said overall security had also been enhanced at major airports across the country.
"The high level of security has not affected the flight operations and the situation is normal," the Islamabad airport manager, Ayaz Jadoon, said.
Security personnel have been asked to step up surveillance and only allow passengers with valid tickets to enter the premises, he added.
The alert came days after a suicide truck bombing at the Marriott Hotel in Islamabad killed at least 53 people, including two US Defense Department officials and the Czech ambassador to Pakistan. More than 270 people were wounded in the attack.
The government believes pro-Taliban militants based in the country's tribal region near the Afghan border carried out the bombing in revenge for major offensives launched against them by the government forces.
DawnNews said the US embassy in Islamabad had suspended its consular services, including visa operations. Britain took similar action earlier this week and British Airways suspended its flights in and out of the country after the Marriott blast.