A hitherto unheard of militant group called the Baluchistan Liberation United Front (BLUF) has threatened to kill Solecki, head of the U.N. High Commissioner for Refugees' office in Quetta, unless the U.N. acts on its demands.

It wants the release of 141 women it says have been detained in Pakistan, information on about more than 6,000 missing persons, and the resolution of the issue of Baluch independence aspirations.

Solecki was kidnapped on Feb. 2 after gunmen ambushed his car and shot dead his driver in Quetta, the provincial capital of southwestern Baluchistan province.

"The United Nations once again appeals to those having John to contact us, if not directly, then through a trusted intermediary," the U.N. said in a statement .

The U.N. said it had been told Solecki's health was failing, and expressed concern that his condition could become life threatening.

The group turned down a U.N. request for direct contact on Wednesday, saying talks were unnecessary.

Baluchistan, the largest but poorest of Pakistan's four provinces, lies on the border with Afghanistan. Separatist militants have fought a low-scale insurgency there for decades.