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KYIV, July 26 (Reuters) - Russian forces have struck port infrastructure in Ukraine's southern Mykolaiv region, Mayor Oleksandr Senkevich said on Tuesday.

"A massive missile strike was launched on the south of Ukraine from the direction of the Black Sea, and with the use of aviation," he told Ukrainian state television, providing no details on the aftermath of the strike.

Last Saturday, Russia struck another southern Ukrainian port of Odesa, casting doubt on a plan to restart Ukrainian grain exports.

The grain deal aims to allow safe passage for grain shipments in and out of Ukrainian ports, blockaded by Russia since its Feb. 24 invasion. Russia has blamed Ukraine for stalling shipments by mining the port waters. (Reporting by Pavel Polityuk Writing by Olzhas Auyezov; Editing by Kim Coghill)