KYIV, June 20 (Reuters) - Ukraine’s military intelligence chief accused Russia on Tuesday of “mining” the cooling pond used to keep the reactors cool at the Russian-occupied Zaporizhzhia nuclear plant in Ukraine’s south.

The six-reactor complex, Europe’s biggest nuclear plant, has been under occupation since shortly after Moscow’s forces invaded in February last year.

“…Most terrifying is that the Zaporizhzhia nuclear plant was additionally mined during that time… namely the cooling pond was mined,” Kyrylo Budanov, head of the GUR agency, said on television, without providing evidence for his assertion.

Reuters requested comment from the Russian defence ministry.

The two sides have accused each other of shelling the plant and its environs, and international efforts to establish a demilitarised zone around the complex have failed so far.

Ukraine’s Defence Ministry, meanwhile, dismissed as “null and void” a Russian suggestion that it could be building a “dirty bomb”.

The ministry said the suggestion, made on Monday by Sergei Naryshkin, the head of Russia’s SVR foreign intelligence service, was first advanced by Moscow last year.

The move was, a ministry statement said, aimed at “diverting attention from the clear defeats by occupation forces at the front and sowing distrust among Ukraine’s Western allies”.