One day after Islamist militants close to the Afghan border said they had killed a Polish geologist, the kidnappers of an American U.N. worker seized in Pakistan have released a video showing the hostage begging the world to help secure his release.

The short grainy video released Friday shows John Solecki, the head of the U.N. refugee agency in the Pakistani border city of Quetta, wearing a blindfold. On the video, Solecki's captors threaten to kill him unless their demands are met.

Solecki says he is "sick and in trouble" and asks the U.N. to help "solve the problem soon" so that he can be freed.

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Pakistan has seen a rash of kidnappings and attacks on foreigners in recent months, mostly blamed on Al Qaeda and Taliban militants seeking to destabilize the secular government and punish it for supporting the U.S.-led war in neighboring Afghanistan.

Solecki was seized last Monday in Quetta in the southern Pakistan province of Baluchistan as he drove to work at the offices of the U.N. refugee agency there.

Quetta's chief investigator Wazir Khan Nasir said a previously unknown ethnic Baluch separatist group called the Baluchistan Liberation United Front telephoned a local journalist Saturday to claim responsibility. He did not say what the group's demands were.

"We are vigorously looking into the matter," Nasir told the AP.

Pakistan-based Online International News Network quoted a spokesman for the front as saying Solecki was kidnapped to highlight the Baluch campaign for independence. The group has demanded the release of 141 Baluch women allegedly detained by Pakistani authorities and that the U.N. "solve the issue of Baluchistan under the Geneva Convention," he said.

He said it was the front's first kidnapping but warned of others if the demands were not met.

The natural-gas-rich region is home to a decades long insurgency, but foreigners had never been targeted previously.

There was no official confirmation Sunday that the Polish hostage, Piotr Stanczak, was dead, but Poland's prime minister, Donald Tusk, said Saturday that Warsaw had received "informal" word that the kidnappers had killed their victim.

A spokesman for Taliban militants operating around the town of Darra Adam Khel in northwest Pakistan said Stanczak was "slaughtered" because the government had missed a deadline to release 26 prisoners. The spokesman, who said he went by the single name Mohammad, said authorities had offered to free only four. He spoke to The Associated Press by telephone from an undisclosed location.

Armed men pulled Stanczak from his car on Sept. 28 after killing three Pakistanis traveling with him near the city of Attock. Stanczak had been surveying oil and gas fields in the region.

If confirmed, Stanczak's death would appear to be the first killing of a Western hostage in Pakistan since U.S. journalist Daniel Pearl was beheaded in 2002.

Two diplomats — an Iranian and an Afghan — as well as a Chinese telecoms engineer are also being held by kidnappers, and an American aid worker was fatally shot in the main northwestern city of Peshawar in November.

Officials say Stanczak's kidnappers have also been demanding the withdrawal of Pakistani security forces from the northwest, where the army is embroiled in fierce fighting against Islamist militants in several regions.