Attorney General Alberto Gonzales said Tuesday that President Bush personally blocked Justice Department lawyers from pursuing an internal probe of the terrorism surveillance program that monitors Americans' international calls and e-mails when terrorism is suspected.

The department's Office of Professional Responsibility announced earlier this year it could not pursue an investigation into the role of Justice lawyers in crafting the program, under which the National Security Agency intercepts some telephone calls and e-mail without court approval.

At the time, the office said it could not obtain security clearance to examine the classified program.

Under sharp questioning from Senate Judiciary Committee chairman Arlen Specter, Gonzales said that Bush would not grant the access needed to allow the probe to move forward.

"It was highly classified, very important and many other lawyers had access. Why not OPR?" asked Specter, R-Pa.

"The president of the United States makes the decision," Gonzales told the committee hearing, during which he was strongly criticized on a range of national security issues by Specter and Vermont Sen. Patrick Leahy, the panel's senior Democrat.

Last week, under a deal with Specter, Bush agreed conditionally to a court review of his antiterror eavesdropping operations.

When the program was disclosed in December, it outraged Democrats and civil libertarians who said Bush overstepped his authority.