The data might have helped determine the nature of the incident and the extent of radioactive contamination — potentially helping people decide whether to take medicine to protect against radiation, such as iodine, but also possibly revealing military secrets about what happened.

Mr. Ryabkov did not directly address the Vienna-based group’s assertion that Russia had stopped sharing the data after the accident. But his comment suggested it was Moscow’s prerogative, and not a coincidental technical fault at four sensors, that caused the disruption.

“It is necessary to keep in mind that handing over the data from the national segment of the international system of monitoring is an entirely voluntary affair for any country,” Mr. Ryabkov said.

The test ban treaty of 1996 is observed by many states but has not formally taken effect, as some countries with nuclear capabilities, including the United States, have not signed or ratified it. Site inspections would only be possible under the treaty after it takes effect. Russia has signed and ratified the treaty.

Mr. Ryabkov added that the incident near Arkhangelsk “should have no relation at all to the activities” of the test ban monitoring group, as the organization’s mandate is limited to identifying possible nuclear explosions. Russian scientists said on Aug. 11 that the accident occurred as they studied “small-scale sources of energy with the use of fissile materials.”

In his first public comments on the accident, Mr. Putin said on Monday that there was “no threat and no rise in radiation level.” He said that “preventive measures are taken so nothing unexpected happens.” He did not clarify what those measures were.