KYIV Ukraine's military spy chief said on Thursday that the threat of a Russian attack on the vast Zaporizhzhia nuclear plant was receding, but that it could easily return as long as the facility remained under occupation by Moscow's forces.

The intelligence chief, Kyrylo Budanov, made the comment in an interview with Reuters after days of warnings by Ukrainian and Russian officials accusing each other of plotting an attack at Europe's largest nuclear plant.

"The threat is decreasing", said Budanov, who is the head of Ukraine's Main Directorate of Intelligence at the Ministry of Defence, declining to say how he was able to say.

President Volodymyr Zelenskiy has for days warned of the grave threat at the facility, most recently saying Russian forces had mined the roof of several reactors.

Budanov did not give details of what had been done to reduce the threat, or what it consisted of. He made clear he believed the threat had only been postponed until later.

"Sorry I can't tell you what happened recently but the fact is that the threat is decreasing", he said. "This means that at least we have all together with joint efforts somehow postponed a technogenic catastrophe".

"It's not eliminated. As long as the station is occupied this can happen again any time if they want", he said.

He also commented on the major counteroffensive which Ukraine launched against Russian occupying forces last month.

"The counteroffensive is in progress. In general, let's just say it's happening. There will be success, but later", he said.

He compared the Ukrainian operation with Russia's months-long battle to capture the eastern city of Bakhmut in April.

"I want to remind you this famous story with Bakhmut. The Russians were attacking it for more than 10 months. Our task is a bit bigger than Bakhmut, but we have a bit less time than 10 months".

(Reporting by Tom Balmforth and Sergiy Karazy; editing by Frank Jack Daniel)