KYIV (REUTERS) - Two employees of Ukraine's Russian-controlled Zaporizhzhia nuclear plant have been detained for passing information to the Ukrainian authorities, Russia's National Guard said on Wednesday (Aug 24).

The National Guard said it had prevented what it called "illegal actions" that threatened the plant's security, and arrested the two staff, who it said had transmitted information to Ukrainian armed forces about the location of personnel and equipment on the site.

It said it also detained a third person who had violated the plant's access procedures, describing them in a statement as "an accomplice of the Armed Forces of Ukraine, who transmitted the coordinates of the movement of columns of Russian equipment".

There was no immediate comment from Ukraine.

The Zaporizhzhia nuclear plant, Europe's largest, was captured by Russian troops in March.

It remains close to the front line, and has come under repeated fire in recent weeks, raising fears of a nuclear disaster.

Both Russia and Ukraine have accused each other of shelling the plant.

Ukrainian staff continue to operate the reactors.

A Ukrainian technician at the site told Reuters last week that staff were working under huge pressure, with heavily armed Russian troops patrolling all parts of the site, but were staying on to ensure there was no Chernobyl-style nuclear disaster.

Mr Vladimir Rogov, an official in the Moscow-installed administration in the Russian-occupied part of Zaporizhzhia region, said two other people - a security guard and an engineer - had been detained on Aug 17 and were accused of helping Ukrainian forces to target attacks on the plant.

Ukraine denies shelling the site and says Russia is using it as a shield to enable it to launch attacks on surrounding territory.

The United Nations has called for the area to be demilitarised and its nuclear watchdog, the International Atomic Energy Agency, is seeking to gain access.