Islamabad - Pakistani investigators were examining evidence Tuesday connected to the kidnapping of a United Nations official in the south-western province of Balochistan the previous day.

Gunmen abducted US citizen John Solecki, local head of the United Nations High Commissioner for Refugees, in the provincial capital Quetta as his Pakistani chauffer drove him to work at around 8:45 am (0345 GMT) without any escort.

The driver died at hospital of bullet wounds he suffered in the attack, which was described by the Pakistani government as an "unfortunate and dastardly terrorist act."

"Several law enforcement agencies have joined the investigations and a task force has been set up to piece together the clues," senior police officer Khalid Masood told Deutsche Presse-Agentur dpa. "There are no leads that we can make public right now."

Police detained about a dozen suspects in overnight raids, but all were found to be innocent, according to another police officer.

UN spokeswoman in Islamabad Ishrat Rizvi said officials were in constant contact with the Pakistani authorities, but declined to give any information.

Strict surveillance of land routes leading outside Quetta was being maintained to check Solecki's transportation by his abductors, the police said.

Balochistan borders Afghanistan and also shares a part of its boundaries with the troubled Waziristan tribal district that serves as a sanctuary for al-Qaeda and Taliban fighters, and is home to top Pakistani militant commander Baitullah Mehsud.

Though the impoverished province has seen little Islamist militancy, ethnic Baloch tribesmen have been involved in a low-level insurgency for several years, seeking more autonomy and a greater share of profits from the vast energy resources exploited in the area.

Solecki's kidnapping came two days before the scheduled visit of UN Secretary-General Ban Ki-moon to Pakistan.

Rizvi said there had been no changes in the UN chief's travel plans yet.

Ban strongly condemned the attacks on UN staff, saying, "Such acts are aimed, not only against UN personnel, but also against those they serve selflessly and with dedication." (dpa)