ISLAMABAD — A spokesman for a Taliban militant group in Pakistan says it has killed a Polish man after holding him hostage for four months.

The spokesman said his group killed the man on Saturday after failing to agree on a prisoner swap with the Pakistani government. The spokesman said he goes only by the name Mohammed.

There was no official confirmation of the man's death.

However, Polish Prime Minister Donald Tusk said earlier in Germany that Warsaw had received "informal information" that the kidnappers had killed the man.

The hostage was an employee of a Polish geophysics institute. He was abducted in northwestern Pakistan on Sept. 28.