WASHINGTON (Reuters) - Nearly all of the thousands of Americans subjected to a domestic surveillance program authorized by President George W. Bush have been dismissed as potential suspects, the Washington Post said on Sunday.

The Bush administration says the surveillance, conducted by the National Security Agency without a warrant, helps defend the United States against terror attacks. Critics say it violates the rights of Americans by eavesdropping on telephone conversations.

According to the newspaper, intelligence officers heard nothing suspicious in the calls and saw no reason to suspect most of the people of improper activity, according to current and former government officials and sources in the private sector familiar with the technology being used.

Each year, fewer than 10 U.S. citizens or residents spark enough interest during the surveillance to cause monitoring of domestic phone calls as well, according to an authoritative account, the newspaper said.

Two sources said thousands of people in the past four years have had their telephone conversation recorded or e-mails read by intelligence analysts.

According to the newspaper, hundreds of thousands of telephone conversations, e-mails and faxes are sifted by computer-controlled systems to determine when intelligence officers will take a hand. Most of the leads were dismissed within days or weeks.

While government officials such as Air Force Gen. Michael Hayden said last month that it was inevitable that some leads would not pay off, some national security lawyers said the large number of communications put under scrutiny would be hard to justify as a permissible intrusion to search for wrongdoers.

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