Threats to UK's Pakistan mission

On alert outside the UK High Commission

A security alert in Pakistan has forced the temporary closure of the British High Commission in Islamabad.

The alert has also led to the US postponing an Independence Day party at its embassy in the city.

A spokesman at the High Commission said that the decision to close down had been made in the interests of staff safety following telephone threats.

Police are trying to trace the origins of the calls and have increased security in the diplomatic area.

Heavily guarded

The BBC's Paul Anderson in Islamabad says that staff at the High Commission would not disclose the nature of the threat but it is clearly being taken seriously.

Pakistani police have beefed up their presence at the building, which is one of many embassies and diplomatic offices situated within a heavily guarded compound.

The head of Pakistani police in charge of security at the compound said they were trying to trace the telephone numbers used to deliver the threat.

Each building has its own security systems - from barbed wire on reinforced concrete walls to sophisticated surveillance and entry systems.

Our correspondent says that after the war in Iraq, American, British and Australian nationals were considered to be the most at risk of attack from targeted reprisals by Islamic extremists in Pakistan.

There were a series of attacks against westerners and Christians which appeared to subside in the immediate aftermath of the war.

But our correspondent says that reports from a number of western sources suggest that the threat of violence is returning.