The United States on December 16 more than doubled its previous reward for information leading to the arrest and conviction of Islamic State leader Abu Bakr al-Baghdadi.
The U.S. State Department's Rewards for Justice program offered $25 million for information that would help locate Baghdadi, up from $10 million it offered in October 2011.
Baghdadi, an Iraqi whose real name is Ibrahim al-Samarrai, declared himself the caliph of a huge swath of Iraq and Syria two years ago. Followers call him "Caliph Ibrahim."
His exact location is not clear. Reports have said he may be in Mosul, Iraq, or in IS-held territory to the west of the city near the border with Syria.
Iraqi officials believe that growing pressure resulting from a coalition military assault on Mosul is causing Baghdadi and his top lieutenants to move around and try to hide themselves.
"Under al-Baghdadi, ISIL has been responsible for the deaths of thousands of civilians in the Middle East, including the brutal murder of numerous civilian hostages from Japan, the United Kingdom, and the United States," the State Department said in announcing the higher bounty on Baghdadi's head.
Based on reporting by AFP and Reuters