KYIV, Aug 20 (Reuters) - President Volodymyr Zelenskyy on Saturday (Aug 20) warned Ukrainians to be vigilant in the coming week as they prepare to celebrate their Independence Day, as fresh blasts hit Crimea and a missile wounded 12 civilians near a nuclear power plant.

In his nightly video address, Zelenskyy said Ukrainians must not allow Moscow to "spread despondency and fear" among them as they mark the 31st anniversary of independence from Soviet rule.

"We must all be aware that this week Russia could try to do something particularly ugly, something particularly vicious," Zelenskyy said ahead of the anniversary on Aug 24, which also marks six months since Russia's full-scale invasion of Ukraine began.

The curfew in Ukraine's second largest city, Kharkiv, would be extended for the entire day on Aug 24, regional governor Oleh Synehub said. The northeastern city is regularly hit by Russian shelling and normally has a curfew from 10pm to 6am.

"Remain at home and take heed of warnings!" Synehub wrote in a message to residents on Telegram.

Also on Saturday, a Russian missile hit a residential area of a southern Ukrainian town not far from a nuclear power station, wounding 12 civilians, Russian and Ukrainian officials said.

That strike at the Pivdennoukrainsk (South Ukraine) nuclear station and fresh shelling near the Zaporizhzhia station, Europe's largest such facility, prompted new fears of a nuclear accident during the war, Ukrainian officials said.

Zelenskyy in his address also referred obliquely to a series of explosions in recent days in Crimea, the Ukrainian territory seized and annexed by Russia during a 2014 incursion.

Ukraine has not claimed responsibility for the attacks, but analysts have said at least some have been made possible by new equipment used by Ukrainian forces.

"You can literally feel Crimea in the air this year, that the occupation there is only temporary and that Ukraine is coming back," Zelenskyy said.

In the latest attack in Crimea, the Russian-appointed governor not recognised by the West said a drone had struck a building near the headquarters of Russia's Black Sea Fleet on Saturday morning.

"A drone flew onto the roof. It was flying low," governor Mikhail Razvozhayev said on Telegram. "It was downed right over the Fleet headquarters. It fell on the roof and burned up. The attack failed."

Razvozhayev said later the region's anti-aircraft system had again been in operation and asked residents to stop filming and disseminating pictures of how it was working.

Ukrainian media reported explosions in nearby towns - including the resorts of Yevpatoriya, Olenivka and Zaozyornoye.