An anti-government activist’s claim that they had destroyed a Russian military surveillance aircraft during a weekend drone strike on an airfield outside of the Belarusian capital Minsk was rejected as false on Tuesday by a senior official in Belarus.

A drone strike on a Russian Beriev A-50 espionage plane was carried out by Belarusian “partisans,” according to Aliaksandr Azarov, head of the anti-government group BYPOL, who was mentioned on Sunday.

He did not provide immediate evidence to back his assertion.

“Given the absence of an official reaction, I am deeply convinced that this is another fake (claim) aimed at highlighting certain failures in our national security,” Belarusian Deputy Foreign Minister Yuri Ambrazevich told Reuters on the sidelines of the U.N. Conference on Disarmament in Geneva on Tuesday.

Belarus has allowed Russia to use its territory to launch attacks on Ukraine but has refrained so far from getting directly involved in the war.

The A-50 plane has the NATO reporting name of Mainstay and is an airborne early warning aircraft with command and control capabilities and the ability to track up to 60 targets at a time.

Britain’s military intelligence service said on Tuesday that attribution for the attack and damage to the aircraft had not been officially corroborated.

“However, the loss of an A-50 Mainstay would be significant as it is critical to Russian air operations for providing an air battlespace picture,” it said in a statement.

“This will likely leave 6 operational A-50s in service, further constraining Russian air operations.”

Reached by telephone on Monday, Azarov told Reuters the operation, which he suggested had caused serious damage to the Russian aircraft, had taken several months to plan and that “partisans” would try to carry out more actions in the future.

BYPOL, his organization, includes former law enforcement officers who support opposition politicians. It has been branded a terrorist organization by Minsk.

The Kremlin has declined to comment on the alleged attack.