QUETTA (Pakistan) - A SIX-MEMBER team of US investigators arrived in the Pakistani city of Quetta on Thursday to probe the kidnapping of a top American UN official, local police and security officials said.

The Federal Bureau of Investigation (FBI) team visited the crime scene for a briefing by Pakistani officials on how John Solecki, head of the UN refugee agency (UNHCR) in Quetta, was kidnapped in the city, a security official said.

Solecki was abducted at gunpoint and his driver killed when his UN vehicle was ambushed on Monday. The incident happened near the UNHCR office.

The FBI officials came for an on-the-spot assessment, asked questions and sketched the scene, the official said.

They later met the police chief of Baluchistan province, Asif Nawaz Waraich, to discuss Pakistani inquiries, a senior police officer said.

Pakistani police and security officials refused to give further details and spoke on condition of anonymity because they were not authorised to talk to the media.

Asked about the reported FBI involved, the US embassy declined to speak on the subject.

'I cannot comment,' spokesman Lou Fintor told AFP in Islamabad.

'We are cooperating with UN and Pakistani authorities to determine the facts,' he added, confirming only that an American working for UNHCR in Quetta had been abducted on Monday.

Pakistani authorities say they have detained more than a dozen people in connection with the kidnapping and offered a reward of one million rupees (12,610 dollars) for information leading to Solecki's rescue.

Baluchistan, in southwest Pakistan on the border with Afghanistan and Iran, is rife with regional insurgency, sectarian violence and attacks blamed on Islamist extremists, making it difficult to pinpoint the kidnappers.

During a visit to Islamabad on Wednesday, UN Secretary General Ban Ki-moon called on Pakistan to do everything possible to secure Solecki's release.

Pakistan has condemned the kidnapping as a 'dastardly terrorist act'. -- AFP