The Russian ministry's release assured that Moscow was in full compliance with the CTBT and urged the United States to do the same.

On Thursday, Russia slammed the United States's allegations that Moscow was carrying out nuclear tests at the Novaya Zemlya archipelago in the Arctic Ocean in violation of a moratorium and countered that Washington was attempting a smear campaign.

“Such accusations are absolutely groundless and aimed at trying again to smear our country,” a statement from the Ministry of Foreign Affairs said, backing up the head of the Russian State Duma Defense Committee, Vladimir Shamanov, who fired back that there "could not have made a more irresponsible statement."

During an address Wednesday, head of the U.S. Defense Intelligence Agency (DIA) speculated — without presenting evidence — that Russia was likely conducting low-level tests at the facility and violating the limit set by the Comprehensive Nuclear Test Ban Treaty (CTBT).

"The United States believes that Russia probably is not adhering to its nuclear testing moratorium in a manner consistent with the ‘zero-yield’ standard."

State Duma Defense Committee chief rubbished the accusation and questioned U.S. intelligence gathering techniques.

"Nuclear tests cannot be carried out secretly," Shamanov added "These kinds of statements reveal that the professionalism of the military is systemically falling in America."

Lassina Zerbo, executive secretary of the Comprehensive Nuclear-Test-Ban Treaty Organisation (CTBTO), later confirmed that the claim by DIA's Lt Gen Robert Ashley have been investigated and are unfounded.

“The only thing I can say is that we don’t have any evidence at this point in time.”

The Russian ministry's release further explained that the U.S. was off base and assured that Russia was in full compliance with the CTBT, which Moscow ratified in 2000, pointing out that the United States had yet to do the same.

“We again call on the United States to show a responsible approach and to ratify the CTBT, without which its entry into force is not possible,” Russia’s statement urged.

The CTBT is widely supported but requires ratification by eight additional nuclear technology states — among them Israel, Iran, Egypt and the United States.

The tensions between the U.S. and Russia could also put the Intermediate-Range Nuclear Forces Treaty, which is due to end in August, and the Strategic Arms Reduction Treaty, which will expire in 2021, into limbo.