A concrete-testing company and its laboratory director have been indicted on charges that they falsified test reports about the strength of concrete at some of New York's largest construction projects, the Manhattan district attorney's office said on Wednesday.

The indictments against the company, Stallone Testing Laboratories, and its director, William Bayer, 69, were announced at a news conference by District Attorney Robert M. Morgenthau. The defendants were later arraigned in State Supreme Court in Manhattan on charges of scheming to defraud and offering a false instrument for filing.

The charges against Stallone Testing, which officials said were part of a continuing investigation into concrete-testing fraud, follow the similar indictment in October of another company, Testwell Laboratories.

Testwell, one of the biggest concrete-testing companies in the New York area, was charged with systematically falsifying its results at projects including the Freedom Tower at ground zero.

"If Testwell is equivalent to Coca-Cola, Stallone would be more like R.C.," said Diana Florence, an assistant district attorney.

Luigi P. DeMaio, a lawyer for Stallone Testing and Mr. Bayer, said the charges were "nonsense," adding, "Everything we tested came out above specifications."

Mr. Morgenthau's office released a list of 90 city projects that have been found to have false mix-design test reports, which indicate the strength of concrete. The projects included the Port Authority Bus Terminal, the World Trade Center transit hub and the Second Avenue subway, plus nursing homes, schools, highways and bridges.

Officials from the Port Authority of New York and New Jersey, the Metropolitan Transportation Authority and the city's School Construction Authority attended the news conference. They indicated that they were in the process of testing the projects on the list that were under their jurisdiction for safety, and so far, nothing had been discovered that was cause for concern.

The investigation into Testwell led the city's Department of Buildings to begin spot-checking concrete labs and pour sites.

Mr. Morgenthau said that test reports seized at Stallone Testing's offices in Port Chester, N.Y., showed that the company was not performing mix-design tests as required by the New York City Building Code.

The tests indicate the strength results for concrete based on the type of sand or cement used, and take weeks to complete. They are necessary before concrete can be poured at any project.

According to the investigation, contractors paid for mix-design tests that were not performed, and that some of Stallone Testing's reports were false "because the results were scientifically impossible," Mr. Morgenthau said.

"The testing is required by law; that safety net was bypassed," the district attorney said. He added that Stallone Testing charged $225 for each report and that contractors "could get a report overnight that would normally take 28 days."

Mr. Bayer - who worked two days a week for $600 a week, according to the district attorney's office - is charged with allowing a Stallone Testing vice president to approve hundreds of mix-design test reports that certified Mr. Bayer had supervised the tests when he had not.

Before the arraignment, Mr. DeMaio described Stallone Testing's mix-testing as a standard operation. "No one is saying we contributed to the building of any unsafe buildings," he said. "I have no idea what they are saying we falsified."

Patrick Dugan, the chief of investigations at the district attorney's office, said that investigators were in the process of identifying the contractors who received the test results and the records they received. "That's the next chapter," he said.