KYIV (Reuters) -Russia attacked Ukraine's energy system and cities in its eastern region with cruise and ballistic missiles on Wednesday morning, Ukraine's energy minister and local officials said.

At least three people were wounded in a missile attack on Kharkiv in northeastern Ukraine on Wednesday morning, Mayor Ihor Terekhov said.

Ukrainian air forces said Kharkiv was attacked by ballistic missiles and regional governor Oleh Syniehubov said on the Telegram messaging app that there were "damages to civilian non-residential infrastructure".

Separately, Dnipropetrovsk Governor Serhiy Lysak said on Telegram: "Since the morning, the Russian army has been massively attacking the Dnipro region. It is trying to destroy the region's power system."

Ukraine's energy minister German Galushchenko said on Facebook that Russia "is massively attacking the power sector" and that the transmission system operator had imposed restrictions on electricity supply to minimise the impact.

Russia has intensified its attacks on the Ukrainian energy sector since spring 2004, damaging almost half of its generating capacity and causing hours-long blackouts throughout the country.

Earlier on Wednesday, the Ukrainian military launched a countrywide air alert in response to Russian cruise missile launches.

Local authorities and the air force reported missile overflights in the eastern, central, southern and western regions.

During a previous massive missile attack on Nov. 17, Russia launched 120 missiles and 90 drones, killing at least seven people and causing severe damage to the power system.

Power distributor DTEK imposed emergency power cuts of up to eight hours across large parts of Ukraine.

(Reporting by Pavel Polityuk; Editing by Raju Gopalakrishnan and Edmund Klamann)