CORRECTED-August pending home sales jump 7.4 pct - NAR

(Corrects after NAR amends reference to low mortgage rates after Fannie, Freddie takeover. Also corrects to show pending sales were based on contract signings in August)

NEW YORK Oct 8 (Reuters) - Pending sales of existing U.S. homes unexpectedly jumped in August to the highest level in over a year, data from a real estate trade group showed on Wednesday.

The National Association of Realtors Pending Home Sales Index, based on contracts signed in August, rose 7.4 percent in August to 93.4 from an updwardly revised index of 87.0 in July.

The August reading was 8.8 percent higher than a year earlier, and the highest level since 101.4 in June 2007.

Economists polled by Reuters ahead of the report were expecting pending home sales to drop by 1.8 percent.

The association's senior economist Lawrence Yun said home buyers responded to improved affordability with home prices low. (Reporting by Lynn Adler, Editing by Chizu Nomiyama)