VIENNA, Nov 26 (Reuters) - A long-awaited U.N. report on whether Iran has in the past carried out work related to nuclear weapons will not reach a definitive conclusion on the subject, the chief of the U.N. nuclear watchdog said on Thursday.

"The report will not be black and white," Yukiya Amano, the director general of the International Atomic Energy Agency, told reporters.

(Reporting By Francois Murphy and Shadia Nasralla) ((Shadia.Nasralla@thomsonreuters.com; +43 153 11 2256; +43 664 390 6505;))