Police in Pakistan say they have arrested at least two foreigners during a raid in the southern city of Karachi.

The officials say the men threw at least three hand grenades at the security forces during the raid, but none was injured.

Karachi has seen violent support for the Taleban

The men surrendered after anti-terrorist police and paramilitary rangers returned several dozen rounds of automatic fire.

At least one man in the house escaped, reportedly with gunshot wounds.

Officials said the nationalities of the two detained foreigners was unclear and investigations were under way to see if they had links to Osama Bin Laden's al-Qaeda network.

The raid was carried out in the Gulshan-e-Maimar district in the outskirts of Karachi.

The owner of the house, a Pakistani, was also taken into custody.

FBI help

The arrested men were being held at a detention centre in Karachi and were to be interrogated on Thursday afternoon.

BBC correspondent in Islamabad, Zaffar Abbas, says Karachi is one of the few places where al-Qaeda and Taleban members are believed to have hidden since the start of the US-led military campaign in Afghanistan more than a year ago.

Al-Qaeda suspect Ramzi Binalshibh was captured in Karachi

In September, several Arab nationals were arrested after a fierce gun battle.

One was later identified as a key al-Qaeda suspect, Ramzi Binalshibh, who was handed over to the United States.

Since then, Pakistani authorities have stepped up the search-and-arrest campaign.

With the help of the FBI, they have detained more than 20 Pakistani and Arab nationals on suspicion of having links with al-Qaeda.

The biggest catch so far was the arrest in March of al-Qaeda's suspected financier, Abu Zubaydah, who was taken into custody in the central city of Faisalabad.