More Americans unexpectedly signed contracts in August to purchase previously owned homes as mounting foreclosures pushed down prices, making homes more affordable.

The index of pending home resales rose 7.4 percent, the most since October 2001, after falling 2.7 percent in July, the National Association of Realtors said Wednesday in Washington. The increase is the fourth so far this year.

"Vulture investors buying foreclosed homes are likely the key driver of the rise," said Ian Shepherdson, chief U.S. economist at High Frequency Economics Ltd. in Valhalla, N.Y., who forecast a 4 percent increase. "But sales are sales and they all take inventory off the market. The key test now is what happens in September and October, but these numbers today are welcome."

The Federal Reserve and other central banks Wednesday cut interest rates as part of a coordinated effort to help ease the worst credit crisis since the Great Depression.

A regional breakdown of the figures shows the South, including Florida, with the smallest increase.

But all four regions saw pending sales increase from July. The West, an area where foreclosures are particularly prevalent, saw the biggest rise in pending sales with an 18.4 percent jump. Resales climbed 8.4 percent in the Northeast, 3.6 percent in the Midwest and 2.3 percent in the South.

Pending resales are considered a leading indicator because they track contract signings. Closings, which typically occur a month or two later, are tallied in a separate report from the Realtors.

Compared with a year ago, pending resales were up in all regions except the South.

"What we're seeing is the momentum of people taking advantage of low home prices, with pending-home sales up strongly in California, Nevada, Arizona, Florida, Rhode Island and the Washington, D.C., region," Lawrence Yun, the group's chief economist, said in a statement.