The amount is larger than the $312 million sought by the U.N. to deal with its expanding role in providing assistance to refugees escaping militants overrunning the country. The contribution was made after U.N. officials publicly expressed disappointment last week over the deficiency in funding for humanitarian needs, by both the Iraq government and international donors.
The statement said Saudi Arabia's King Abdullah provided the funding to aid Iraqis "who have suffered greatly from recent events, including those who have been displaced, regardless of their religion, sect or ethnicity."
Some analysts have blamed Saudi Arabia -- a Sunni Islam stronghold that has armed Sunni militants in Syria -- for the violence that has overflowed into Iraq.
Iran, led by Shiite Muslims, is Saudi Arabia's regional rival for influence, and has provided military assistance to help stop militants gaining ground in Iraq.