Islamabad - Authorities enhanced security Friday in Pakistan's capital, Islamabad, after sounding a security alert in the wake of renewed terrorist threats, officials said. The United States embassy temporarily suspended its visa and consular services "due to heightened security" with instructions for US diplomats to avoid unnecessary movement and venturing out in public.

American citizens could contact the embassy in case of emergencies, but routine services would resume Monday, an embassy statement said.

Embassy operations were scaled down only in Islamabad while the US consulates in Lahore, Karachi and Peshawar remained open.

Senior police officials did not give specific details about the security threats, but the developments coincided with Good Friday, a major Christian holiday ahead of Easter on Sunday.

Islamabad has been the scene of deadly terrorist strikes in a recent wave of violence by Islamist militants based in the country's volatile north-western region.

Eight paramilitary troops were killed last weekend when a lone suicide bomber struck a makeshift camp on the edge of the capital's most upmarket neighbourhood.

Authorities said they fear Islamabad could be targeted by militant groups in commando-style operations - a pattern that was observed in two attacks carried out in Lahore last month.

The fresh threats followed the arrests of at least four suspected terrorists in overnight raids, the English-language The News daily said.

Some private schools, mostly serving Pakistan's elite, also were closed after receiving warnings from unknown sources, media reports said.

Additional security was also thrown around Islamabad's already cordoned-off "Red Zone," which houses diplomatic missions and key government buildings, including parliament.

A senior Taliban commander said Sunday that militants would be carrying out two bombings every week in revenge for US drone attacks on Pakistan's tribal region bordering Afghanistan.

"The warnings by militants cannot be ignored," the Geo News television channel quoted Pakistani Interior Ministry's top official, Rehman Malik, as saying. (dpa)