UN Secretary-General Kofi Annan on Thursday called for the "immediate and unconditional" release of all Iraqi and foreign hostages taken by Iraqi militants.

Annan "calls for their immediate, safe and unconditional release, and strongly reiterates his appeal to all sides to respect at all times the fundamental principles of international humanitarian law," his spokesman Stephane Dujarric said.

"The secretary general is dismayed by the recent wave of kidnappings in Iraq," the spokesman added.

Annan's comments came as an Internet statement by The Islamic Army in Iraq claimed it had killed a US hostage named Ronald Schulz, who was a contractor.

The video broadcast on Al-Jazeera television on Tuesday showed the cover of a US passport and a bank card with the name of "Ronald Schulz."

The Islamic Army said it killed Schulz because US President George W. Bush refused to meet its demands that all prisoners in Iraq be released.

The Islamic Army, an extremist Sunni group, has claimed responsibility for several kidnappings and murders in Iraq.

At least seven Western hostages have been kidnapped in the country in the past two weeks in another wave of abductions.

Around 40 foreigners remained missing or reportedly kidnapped since a spate of abductions first occurred in Iraq in April 2004.

Source: Xinhua