UPDATE 1-Russia says it thwarts another major Ukrainian offensive in Donetsk

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June 6 (Reuters) - Russia's defence ministry said early on Tuesday that it had thwarted another major offensive by Ukrainian forces in Donetsk, inflicting huge personnel losses and destroying eight main battle Leopard tanks as Kyiv forces pressed on.

"Having suffered heavy losses the day before, the Kiev regime reorganized the remnants of the 23rd and 31st mechanized brigades into separate consolidated units, which continued offensive operations," the ministry said on its Telegram channel.

"A complex fire defeat was inflicted by army forces, assault and operational-tactical aviation, missile forces and artillery, as well as heavy flamethrower systems."

On Monday, Russia said that Ukraine forces had begun a major offensive in the southern region of Donetsk, although it was unclear whether the attack formed the beginning of Ukraine's long-anticipated counteroffensive.

Ukrainian officials have made no mention of any broad, significant new campaign and sidestepped questions on the matter on Monday.

In a promotional video released on Sunday and urging silence in regards to any military actions, Ukraine's defence ministry said "the beginning will not be announced."

Russia's defence ministry said Russian forces destroyed 28 tanks, including eight main battle Leopard tanks supplied to Ukraine by its Western allies, as well as 109 armoured vehicles. It also said that the total Ukrainian losses amounted to 1,500 troops.

There was no immediate comment from Kyiv about Russia's assertions.

Russia - and Ukraine - have often made claims of inflicting heavy human losses on each other which could not be independently verified.

(Reporting by Lidia Kelly in Melbourne and Ron Popeski in Winnipeg; Editing by Leslie Adler and Rosalba O'Brien)