Missiles tore into intersections, parks and tourist sites in the capital Kyiv and explosions were reported in Lviv, Ternopil and Zhytomyr in western Ukraine, Dnipro and Kremenchuk in the centre, Zaporizhzhia in the south and Kharkiv in the east.

Ukrainian officials said at least 11 people were killed and scores injured, with swathes of the country left without power.

Thousands of residents raced to bomb shelters as air raid sirens rang out through the day.

The barrage of dozens of cruise missiles fired from air, land and sea was the biggest wave of air strikes to hit locations away from the front line – at least since the initial volleys on the war’s first day, February 24.

President Vladimir Putin said he had ordered “massive” long range strikes after an attack on the bridge linking Russia to the annexed Crimean peninsula over the weekend and threatened more strikes in future if Ukraine hits Russian territory.

“To leave such acts without a response is simply impossible,” he said, alleging other unspecified attacks on Russian energy infrastructure.

Ukrainian military intelligence claimed the Russian attacks were ordered in early October.

“The objects of critical civil infrastructure and the central areas of densely populated Ukrainian cities were identified as targets,” it said.

Ukrainian President Volodymyr Zelenskiy said they were deliberately timed to kill people as well as to knock out Ukraine’s power grid.

His prime minister said 11 major infrastructure targets were hit in eight regions, leaving swaths of the country with no electricity, water or heat.

“They are trying to destroy us and wipe us off the face of the earth,” Zelenskiy said.

“These attacks killed and injured civilians and destroyed targets with no military purpose. They once again demonstrate the utter brutality of Mr Putin’s illegal war on the Ukrainian people,” US President Joe Biden said in a statement.

“This constitutes another unacceptable escalation of the war and, as always, civilians are paying the highest price,” United Nations spokesman Stephane Dujarric said in a statement.

The Kremlin was humiliated two days ago when a blast damaged the bridge it built after seizing Crimea in 2014.

Ukraine, which views the bridge as a military target sustaining Russia’s war effort, celebrated the blast without officially claiming responsibility.

US Secretary of State Antony Blinken called the strikes “horrific” and he and Biden reiterated US support for Ukraine.

By mid-morning, Ukraine’s defence ministry said Russia had fired 81 cruise missiles, and Ukraine’s air defences had shot down 43 of them.

Russia’s defence ministry said it had hit all its intended targets.

Zelenskiy said the strikes had two main targets: energy infrastructure and people.

“Such a time and such targets were specially chosen to cause as much damage as possible,” he said in a video message filmed on a mobile phone on an empty central Kyiv street.

Prime Minister Denys Shmygal promised to restore utilities as quickly as possible.

Foreign Minister Dmytro Kuleba tweeted: “Putin is a terrorist who talks with missiles.”

In another sign of possible escalation, Putin’s closest ally, President Alexander Lukashenko of Belarus, said he had ordered troops to deploy jointly with Russian forces near Ukraine, which he accused of planning attacks on Belarus with its allies.

He allowed Russia to use Belarus as a staging ground early in the war but has not sent in his troops.

-AAP