Pakistani and US security officials have arrested 12 suspected Muslim militants in North-West Frontier Province near the Afghan border.

The police say the suspects were arrested from the basement of a building in Peshawar, which had until recently been occupied by a banned militant group, the Harkat-ul-Mujahideen.

Police believe the militants were working with al-Qaeda and Taleban fugitives to carry out attacks inside Pakistan.

The FBI has been active in Pakistan since late last year when it set up an office to check the background of airline passengers flying from Pakistan to the USA.

Questioning

Pakistan has consistently denied that FBI agents are helping on the ground.

The BBC's Haroon Rashid in Peshawar says local police have refused to give details of how many US agents were involved in the raid.

Much militant anger is aimed at the US

Police say officers recovered a cache of assault rifles, explosives, detonators and timing devices from the building.

They say four of those arrested are Pakistanis and one an Afghan, while the remaining seven are believed to be Arabs.

An anti-terrorism court has remanded them in police custody for five days for questioning.

The overnight raid coincided with a visit to Peshawar by the new US ambassador to Pakistan, Nancy Powell, who has been meeting local politicians amid stringent security.

US help

As opposition to President Musharraf's support for the US-led "war against terror" mounted and militant attacks against government and Western targets increased, FBI agents have worked closely with their Pakistani counterparts to hunt down Islamist suspects.

Islamabad is loath to admit it, but FBI agents have been involved in a number of investigations following militant attacks across Pakistan in recent months.

Their best-known success came earlier in the year when Pakistani intelligence officers and FBI men arrested several militants, including senior al-Qaeda figure, Abu Zubayda, in the city of Faisalabad.

The Daniel Pearl murder inquiry and the investigation into the bombing of the US consulate in Karachi are two other high-profile cases.

Militant links

The suspects have been handed over to Pakistan's multi-agency Joint Interrogation Team which will try to identify the men and establish their links, if any, to Osama Bin Laden's al-Qaeda network.

General Musharraf is unpopular with some

Since the collapse of Afghanistan's Taleban authorities last year, a number of fighters from both Taleban and al-Qaeda forces are thought to have crossed the border into Pakistan.

There is considerable support for both groups in the fiercely independent Pashtun-dominated tribal areas where similar raids have proved equally successful in the past.

Harkat-ul-Mujahideen is a militant group believed to have had close operational links to al-Qaeda.

It is known to be active in Indian-administered Kashmir where a violent campaign against Indian rule has killed thousands over the past 13 years.