The Pentagon said yesterday that inadequately tested electrical parts, called chips, manufactured by Texas Instruments Inc. have put a "serious" question mark over the reliability of thousands of the nation's most sophisticated weapons.

Millions of the company's 4,700 different versions of the chips are so suspect that the Pentagon has ordered its procurement officers not to accept delivery of weapons containing them, Donald Moore, a quality control executive at the Defense Logistics Agency, said at a news briefing yesterday.

Norman P. Neureiter, a Texas Instruments vice president, said yesterday that "it is a testing issue. We believe that there will be very few, if any, systems problems" in weapons containing chips that were not fully tested.

Moore told reporters that the Pentagon does not know whether it has significant reliability or performance problems but that a Texas Instruments chip with a broken electrical circuit caused the computer system on the Discovery space shuttle to "hiccup" last month, forcing a postponement of the launching.

Moore said the Pentagon is confronted with something "pretty serious" but has not conducted tests that would enable it to judge whether weapons that include the Texas Instruments chips might not work in training or combat.

Pentagon spokesman Michael Burch said at the same briefing that there is "the possibility" of a criminal investigation into Texas Instruments' testing procedures on chips sold to defense contractors.

The Pentagon spotlight on Texas Instruments comes as the administration is under attack by critics in Congress and elsewhere for allowing military contractors to charge inordinately high prices for such simple items as hammers and spare parts. The Pentagon also has moved against other contractors for shoddy performance.

Moore said the problem with the shuttle chip came four months after IBM had discovered that 15 million Taiwan-made chips that it had bought over an eight-year period from Texas Instruments had not been tested adequately.

IBM first discussed its findings with Texas Instruments, Moore said, but apparently could not resolve the problem at that level and reported the situation to the Pentagon.

"They really came to protect themselves," Moore said, referring to IBM. Texas Instruments, he charged, showed "lack of discipline" in not following its own testing program before delivering its chips to IBM and other contractors. This situation looks "pretty serious to me," Moore said.

"Fifteen million is the example at IBM," Moore said in declaring that he has no estimate of the total number of inadequately tested chips that may be in weapons. More than 80 other defense contractors may have purchased as many as 4,700 types of chips from Texas Instruments, he said.

Contractors, in building weapons, often seek permission to use parts available on the civilian market that are cheaper but not always rugged or reliable enough to meet military specifications. Asked if the current situation involves an argument to insist on parts that meet military specifications, Moore replied, "It sure as hell is."

Asked how so many chips could go out before being tested by the supplying company, he said, "I can't answer for executives who don't pay any attention to their responsibilities."

Asked why the government, rather than IBM, did not detect the alleged failure of Texas Instruments to conduct the required tests on its parts, Pentagon officials said prime contractors are responsible for ensuring that parts in their finished products meet reliability standards before being delivered to the government.

Neureiter said his firm is going through its records to determine if delivered chips were tested in conformance to the standards set down by the contractor. He said failure to conduct every one of the testing steps specified by the contractors does not mean the weapon would not work. "We have been conducting an in-depth review of all our testing procedures since early this year," Moore said.