Gaza Strip ? The shadowy Palestinian group that kidnapped a British reporter threatened Tuesday to kill him, adding freedom for an al-Qaida-linked prisoner to its list of demands and charging that Hamas detained two of its members.

In a statement e-mailed to reporters late Tuesday, the Army of Islam said British Broadcasting Corp. correspondent Alan Johnston will be “slaughtered like a sheep” if its demands are not met.

The message demanded that Abu Mohammed al-Maqdisi, who is being held in Jordan, be released. Al-Maqdisi is known as the spiritual mentor of the late al-Qaida leader Abu Musab al-Zarqawi.

In its message, the Palestinian group also called the Hamas arrest of two of its members a “declaration of war.”

In response, Ghazi Hamad, spokesman for deposed Prime Minister Ismail Haniyeh of Hamas, said: “We reject the continued captivity of Alan and we are still working to release him at the soonest possible opportunity.”