Russia 'moving injured troops out of hospitals in Kherson region' and cancels UN-brokered Ukraine export deal

Russian troops have moved large numbers of sick and wounded comrades from hospitals in southern Ukraine's Kherson region, Ukrainian military officials have said.

It comes as Kyiv's forces fight to retake a province that was overrun early in the war.

Kremlin-installed authorities in the mostly Russian-occupied region previously urged civilians to leave the city of Kherson, the region's capital.

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The Moscow-appointed authorities were reported to have abandoned the city, joining tens of thousands of residents who fled to other Russia-held areas ahead of an expected advance by Ukrainian forces.

"The so-called evacuation of invaders from the temporarily occupied territory of the Kherson region, including from medical institutions, continues," the General Staff of the Armed Forces of Ukraine said in a morning update.

"All equipment and medicines are being removed from Kherson hospitals."

Watch: Ukraine offensive wearing down the Russians, defence expert says.

Ukrainian President Volodymyr Zelensky said in his nightly video address on Friday that the Russians were "dismantling the entire health care system" in Kherson and other occupied areas.

"The occupiers have decided to close medical institutions in the cities, take away equipment, ambulances, just everything," he said.

"They put pressure on the doctors who still remained in the occupied areas for them to move to the territory of Russia."

Kherson is one of four regions of Ukraine that Russian President Vladimir Putin illegally annexed last month and where he subsequently declared martial law. The others are Donetsk, Luhansk and Zaporizhzhia.

It comes as Russia's Ministry of Defence said Moscow has moved to suspend its implementation of a UN-brokered grain export deal which has seen more than nine million tons exported from Ukraine and brought down global food prices.

The ministry cited an alleged Ukrainian drone attack against Russia's Black Sea Fleet ships moored off the coast of occupied Crimea, which Russia says took place early on Saturday, as the reason for the move.

Watch: Ukrainian people 'will not fall' amid Russian drone attacks, Zelensky says.

Kremlin-installed authorities in Crimea reported a drone attack on Sevastopol, the largest city on the peninsula annexed by Russia in 2014.

"The ships of (Russia's) Black Sea Fleet are repelling a drone attack in the waters of the Sevastopol Bay," the Russia-appointed governor of Sevastopol, Mikhail Razvozhaev, said.

Ukraine has denied the attack.

Last month, Ukraine's army chief claimed responsibility for a series of missile and drone strikes on Russian air bases in Crimea, including one that tore through a military facility. Kyiv and Moscow have said Ukrainian partisans are active in the area.

The Russian declaration to suspend the trade deal came one day after UN chief Antonio Guterres urged Russia and Ukraine to renew the deal.

Russia's UN Ambassador Vassily Nebenzia said before Moscow discusses a renewal "Russia needs to see the export of its grain and fertilisers in the world market, which has never happened since the beginning of the deal".