WASHINGTON, June 19  Lawmakers say they plan to dig deeper into the Bush administration’s use of bill-signing statements as ways to circumvent Congressional intent.

In a limited examination of the administration’s practice of reserving the authority to interpret legislation, the Government Accountability Office determined that in 6 out of 19 cases it studied, the administration did not follow the law as written after President Bush expressed reservations about some legislative directives. By using signing statements, the president has reserved the right not to enforce any laws he thinks violate the Constitution or national security, or that impair foreign relations.

The accountability office, a watchdog agency, in a report issued Monday, did not pass judgment on whether the agencies were responding to the signing statements or whether the president had the constitutional authority not to comply. But Congressional officials said Tuesday that the findings were alarming since the administration had apparently not complied with the law in 30 percent of the cases scrutinized.

“Federal law is not some buffet line where the president can pick parts of some laws to follow and others to reject,” said Senator Robert C. Byrd, Democrat of West Virginia and chairman of the Appropriations Committee, one of two senior lawmakers who sought the review.