A signing statement attached to postal legislation by President George W. Bush last month may have opened the way for the government to open mail without a warrant.

The White House denies any change in policy.

The law requires government agents to get warrants to open first-class letters.

But when he signed the postal reform act, Bush added a statement saying that his administration would construe that provision "in a manner consistent, to the maximum extent permissible, with the need to conduct searches in exigent circumstances."

"The signing statement raises serious questions whether he is authorizing opening of mail contrary to the Constitution and to laws enacted by Congress," said Ann Beeson, an attorney with the American Civil Liberties Union. "What is the purpose of the signing statement if it isn't that?"