The chairman of the D.C. Council’s education committee on Tuesday accused city officials of manipulating scores on the city’s 2013 standardized tests.

The issue arose at a monthly breakfast for council members and Mayor Vincent C. Gray (D), during a briefing in the wake of a Washington Post report that revealed city officials scored the tests — newly aligned to tough Common Core standards — in a way that allowed them to announce historic gains in both math and reading.

A different grading scale, which teachers and specialists developed for the new tests, would have yielded a gain in reading but a decline in math. The Office of the State Superintendent for Education declined to use that scale after seeing how it would affect scores.

OSSE officials said they wanted to preserve the ability to compare scores across years and to avoid shocking the system with a new grading scale just two years before the city is scheduled to introduce a completely new test.

Education Committee Chairman David A. Catania (I-At Large), who said his staff has been scrutinizing the decision during the past six weeks, saw it as a politically motivated effort to inflate schools’ progress.

“OSSE was content with misleading the public,” said Catania, who interrupted the session several times to challenge officials’ version of events and to question Gray’s “fist-pumping ceremony” announcing test score gains in July.

Gray’s spokesman, Pedro Ribeiro, said the mayor had no hand in the decision about the scoring of the tests. He called Catania’s accusations “absurd” and argued that the council member is the one motivated by politics.

“He’s more likely to find the Loch Ness monster than he is to find some conspiracy here,” ­Ribeiro said. “What you have here is a decision made in good faith by career bureaucrats making decisions in the best interest of the District.”

The back-and-forth over the city’s testing program — the D.C. Comprehensive Assessment System, or D.C. CAS — offered a preview of a council committee hearing scheduled for Thursday on the same subject.

Catania said he will press OSSE to publish test results that would have been reported under the grading scale officials rejected. He also is pushing for disciplinary action against OSSE employees who were involved in the decision.

Catania said he sees the decision as a “form of cheating” meant to derail the seven education bills he introduced in early June, when he argued that D.C. schools aren’t improving fast enough and need an overhaul.

“The council has a right and obligation to ask questions,” ­Ribeiro said. “What the council does not have a right to do is to accuse people of cheating.”

The controversy could have a lasting effect on bills that emerge from the education committee. Catania, who has often cited D.C. CAS scores as a proxy for school performance, said that digging into the inner workings of testing has changed his views on how scores should be used.

“To have decisions about whether or not schools stay open, about whether or not teachers get raises, about whether or not children advance — to have them all built on a system that is so subjective is an overreach,” Catania said.

He said he does not support retreating from tests altogether but would like to see tests serve as “one of our many tools to evaluate the success of our system, and not the be-all and end-all.”

“We cannot view them as the Holy Grail,” Catania said. “It’s become very easy for us to believe that tests equal quality, and they do not, in my opinion.”