(Recasts with drone attacks, new aid coming from Washington, Zelenskiy address)
* Half of Russia's Black Sea aviation wiped out - Western official
* Kyiv coy over incidents in Crimea and Russia
* Ukraine fears Russia will decouple nuclear plant from grid
* Washington prepares more military aid for Kyiv
By Tom Balmforth and Max Hunder
KYIV, Aug 19 (Reuters) - Russia reported fresh Ukrainian drone attacks on Friday evening, a day after explosions erupted near military bases in Russian-held areas of Ukraine and Russia itself, apparent displays of Kyiv's growing ability to pummel Moscow's assets far from front lines.
The latest incidents followed huge blasts last week at an air base in Russian-annexed Crimea. In a new assessment, a Western official said that incident had rendered half of Russia's Black Sea naval aviation force useless in a stroke.
Russia's RIA and Tass news agencies, citing a local official in Crimea, said it appeared Russian anti-aircraft forces had been in action near the western Crimean port of Yevpatoriya on Friday night. Video posted by a Russian website showed what appeared to be a ground-to-air missile hitting a target. Reuters was unable immediately to confirm the video's veracity.
Tass cited a local official as saying Russian anti-aircraft forces knocked down six Ukrainian drones sent to attack the town of Nova Kakhovka, east of the city of Kherson. Ukraine says retaking Kherson is one of its main priorities. Separately, an official in Crimea said defences there had downed an unspecified number of drones over the city of Sevastopol.
"The Ukrainian armed forces treated the Russians to a magical evening," said Seriy Khlan, a member of Kherson's regional council disbanded by Russian occupation forces.
The night before, multiple explosions had been reported in Crimea - which Moscow seized in 2014 - including near Sevastopol, headquarters of Russia's Black Sea Fleet, as well as at Kerch near a huge bridge to Russia.
Inside Russia, two villages had been evacuated after explosions at an ammunition dump in Belgorod province, more than 100 km (60 miles) from territory controlled by Ukrainian forces.
Kyiv has been withholding official comment on incidents in Crimea or inside Russia while hinting that it is behind them using long-range weapons or sabotage.
A Western official indicated on Friday that at least some of the incidents were Ukrainian attacks, saying Kyiv was consistently achieving "kinetic effects" deep behind Russia's lines.
Huge explosions on Aug. 9 at Russia's Saky air base on the Crimean coast had put more than half of the Black Sea Fleet's combat jets out of use, the official said, in what would be one of the costliest attacks of the war.
Russia has denied aircraft were damaged in what it called an accident, although satellite pictures showed at least eight burnt-out warplanes and several huge craters.
Moscow dismissed the head of the Black Sea Fleet this week.
Ukraine hopes its apparent new-found ability to hit Russian targets behind the front line can turn the tide in the conflict, disrupting supply lines Moscow needs to support its occupation.
A senior U.S. defense official said on Friday that U.S. President Joe Biden's administration was preparing another security assistance package for Ukraine valued at $775 million and containing surveillance drones and for the first time mine-resistant vehicles.
Since last month, Ukraine has been fielding Western-supplied rockets to strike behind Russian lines. Some explosions reported in Crimea and Belgorod were beyond the range of ammunition Western countries have acknowledged sending so far.
A senior Ukrainian official said around half of incidents in Crimea were Ukrainian attacks of some kind, and half accidents caused by Russia's poor operations. He emphasised that attacks were carried out by saboteurs rather than long-range weapons, though he would not say whether Kyiv now had ATACMS, a longer range version of the U.S. HIMARS rockets it began using in June.
The official, who declined to be named, said Ukraine had hoped its strikes would have a bigger impact in reducing Russian artillery power but Moscow was adapting.
CONCERN ABOUT NUCLEAR PLANT
Ukraine also issued dire warnings about a frontline nuclear power station, the Zaporizhzhia complex, where it said it believed Moscow was planning a "large-scale provocation" as justification to decouple the plant from the Ukrainian power grid and connect it to Russia's.
"If the Russian blackmail with radiation continues, this summer may go down in the history of various European nations as one of the most tragic of all time. Because no nuclear power station anywhere in the world has a procedure for a terrorist state turning a nuclear power plant into a target," Ukrainian President Volodymyr Zelenskiy said in an address Friday evening.
Continuing the mutual blame game, Russian President Vladimir Putin accused Ukraine of shelling the complex, risking a nuclear catastrophe.
Ukraine's nuclear power operator said on Friday it suspected Moscow was planning to switch over the Zaporizhzhia plant to Russia's power grid, a complex operation Kyiv says could cause a disaster.
The power station is held by Russian troops on the bank of a reservoir. Ukrainian forces control the opposite bank.
Moscow has rejected international calls to demilitarise the plant and Putin on Friday renewed his accusation that Kyiv was shelling it in a phone call with French President Emmanuel Macron, according to the Kremlin's readout.
Macron's office said Putin agreed to a mission to Zaporizhzhia by the International Atomic Energy Agency (IAEA).
Thousands of people have been killed and millions forced to flee since Russia launched its invasion on Feb. 24, saying it aimed to demilitarize Ukraine and protect Russian speakers on what Putin called historical Russian land.
Ukraine and Western countries view it as a war of conquest aimed at wiping out Ukraine's national identity.
(Reporting by Reuters bureaux; Writing by Peter Graff, Andrew Cawthorne and Patricia Zengerle; Editing by Philippa Fletcher, Tomasz Janowski and Daniel Wallis)