(Recasts with Kyiv, Moscow trading blame, adds quotes on IAEA visit)
* Kyiv warns of Chornobyl-style disaster unless area secured
* Both sides say in favour of visit by nuclear inspectors
* UN's Guterres says any attack on a nuclear plant is 'suicidal'
* Two Ukrainian grain ships leave ports, 12 since last week
By Natalia Zinets and Max Hunder
KYIV, Aug 8 (Reuters) - International alarm over the weekend shelling of Ukraine's Zaporizhzhia nuclear complex grew on Monday, as Kyiv and Moscow traded blame for the attacks while seeking to address fears that their battle for control of the plant might trigger catastrophe.
United Nations chief Antonio Guterres, calling any attack on a nuclear plant a "suicidal thing", demanded that U.N. nuclear inspectors be given access. The largest complex of its kind in Europe, Zaporizhzhia is situated in a southern region seized by Russian invaders in March and now targeted by Ukraine for a counter-offensive.
Kyiv appealed for the area to be demilitarised and for the International Atomic Energy Agency, the U.N.'s nuclear watchdog, to be let in. Russia's foreign ministry said it too favoured an IAEA visit, which it accused Ukraine of blocking while trying to "take Europe hostage" by shelling the plant.
Ukraine blamed Russia for weekend attacks in the area of the complex, which is still run by Ukrainian technicians. It said three radiation sensors were damaged, with two workers hospitalised with shrapnel injuries.
Reuters could not verify either side's version of what happened.
Petro Kotin, head of Ukraine's state nuclear power company Energoatom, called for peacekeepers to be deployed in and run the Zaporizhzhia site, with operational control handed back to Ukraine.
He flagged the danger of shells hitting containers of highly radioactive spent nuclear fuel as especially dire. If two or more containers were broken, "it is impossible to assess the scale" of the resulting disaster.
"Such insane actions could leave to the situation spiralling out of control and it will be a Fukushima or Chornobyl," Kotin said.
'WORKING UNDER RUSSIAN GUNS'
Yevhenii Tsymbaliuk, Ukraine's ambassador to the IAEA, said Zaporizhzhia staff were "working under the barrels of Russian guns". He called for a U.N.-led international mission to the plant by the end of August and accused Russia of trying to cause blackouts along Ukraine's southern electricity grid by targeting the plant.
The Russian defence ministry meanwhile said Ukrainian attacks had damaged high-voltage power lines servicing the Soviet-era plant and forced it to reduce output by two of its six reactors to "prevent disruption".
A Russian-installed official in the Zaporizhzhia region earlier said the facility was operating normally.
The U.N.'s Guterres said IAEA personnel needed access to Zaporizhzhia to "create conditions for stabilisation".
"Any attack (on) a nuclear plant is a suicidal thing," he told a news conference in Japan, where he attended the Hiroshima Peace Memorial Ceremony on Saturday to commemorate the 77th anniversary of the world's first atomic bombing.
The world's worst civil nuclear disaster occurred in 1986 when a reactor at the Chornobyl complex in northwest Ukraine exploded. Soon after this year's Feb. 24 invasion Russian troops occupied that site, withdrawing from the area in late March.
Ukraine has said it is planning to conduct a major counter-offensive in the Russian-occupied south, apparently focused on the city of Kherson, west of Zaporizhzhia, and that it has already retaken dozens of villages.
GRAIN EXPORTS PICK UP STEAM
Nearby, a deal to unblock Ukraine's food exports and ease global shortages gathered pace as two grain ships sailed out of Ukrainian Black Sea ports on Monday, raising the total to 12 since the first vessel left a week ago.
The two latest outgoing ships were carrying almost 59,000 tonnes of corn and soybeans and were bound for Italy and southeastern Turkey. The four that left on Sunday bore almost 170,000 tonnes of corn and other food.
The July 22 grain export pact brokered by Turkey and the United Nations represents a rare diplomatic triumph as fighting churns on in Ukraine. The deal aims to help ease soaring global food prices arising from the war.
Before the invasion, Russia and Ukraine together accounted for nearly a third of global wheat exports. The disruption since then has raised the spectre of famine in parts of the world.
Ukraine has said it hopes to export 20 million tonnes of grain in silos and 40 million from its new harvest to help rebuild its wrecked economy.
Russia says it is waging a "special military operation" in Ukraine to rid it of nationalists and protect Russian-speaking communities. Ukraine and the West describe Russia's actions as an unprovoked imperial-style war to reassert control over a pro-Western neighbour lost when the Soviet Union broke up in 1991.
The conflict has displaced millions, killed thousands of civilians and left cities, towns and villages in ruins.
Russian forces are trying to gain full control of Ukraine's eastern Donbas region where pro-Moscow separatists seized territory after the Kremlin annexed Crimea to the south in 2014.
"Ukrainian soldiers are firmly holding the defence, inflicting losses on the enemy and are ready for any changes in the operational situation," Ukraine's general staff said in an operational update on Monday.
Russian forces stepped up attacks north and northwest of Russian-held Donetsk city in the Donbas on Sunday, Ukraine's military said.
(Reporting by Reuters bureaus; Writing by Stephen Coates, Mark Heinrich, John Stonestreet; Editing by Simon Cameron-Moore, Nick Macfie, Peter Graff)