WASHINGTON (Reuters) - Contracts to buy U.S. previously owned homes rebounded marginally in February amid a decline in mortgage rates but rising economic uncertainty could limit momentum.

The National Association of Realtors (NAR) said on Thursday its Pending Home Sales Index, based on signed contracts, rose 2.0% to 72.0. Economists polled by Reuters had forecast contracts, which become sales after a month or two, rebounding 1.0%. Pending home sales decreased 3.6% from a year earlier.

"Despite the modest monthly increase, contract signings remain well below normal historical levels," said Lawrence Yun, the NAR's chief economist.