A shadowy group holding a British correspondent for three months threatened on Sunday to kill him, in a video broadcast by the Al-Jazeera satellite TV channel.
A spokesman for The Army of Islam, identified as Abu Khattab, told Al-Jazeera that there was no deal to release BBC correspondent Alan Johnston, and " if the situation gets more complicated concerning us and our group, then we will ingrate ourselves to Allah by slaying this journalist."
The authenticity of the video could not be independently confirmed. Earlier, a Hamas spokesman in Gaza said there had been no new developments in the case, despite reports that Johnston would be released soon.
Johnston was abducted from a Gaza City street on March 12.