Washington, May 6 (IANS): The US administration has posted a bounty of $20 million for information on four key figures of the Islamic State (IS), an extremist group it is fighting in Iraq and Syria.

The State Department is seeking tips that can lead to the arrest of Abd al-Rahman Mustafa al-Qaduli, Abu Mohammed al-Adnani, Tarkhan Tayumurazovich Batirashvili and Tariq Bin-al-Tahar Bin al Falih al-Awni al-Harzi.

Al-Qaduli, once a deputy to the leader of Al Qaeda in Iraq Abu Musab al-Zarqawi, rejoined the IS following his release from prison in early 2012 and is operating from Syria, Xinhua news agency cited the State Department as saying in a statement on Tuesday.

Al-Adnani is the group's official spokesman, Batirashvili is serving as a senior commander, while al-Harzi is described as the leader for the border region between Syria and Turkey and chief of its suicide bombers.

Last year, they were branded as specially designated global terrorists by the US Department of Treasury.

Washington is leading airstrikes on the IS targets inside Iraq and Syria, with a view to "degrading and ultimately destroying" it, as the group has established a "caliphate" in areas under its control in the two Arab countries.