By Andrew Osborn

MOSCOW (Reuters) -Russia's Defence Ministry said on Tuesday it had hit military targets in two Ukrainian port cities overnight as "a mass revenge strike" in response to an attack on the Crimean bridge the previous day which it blamed on Kyiv.

The ministry said it had struck Odesa, where the Ukrainian navy has its headquarters, and Mykolaiv, near Ukraine's Black Sea coast.

"The armed forces of the Russian Federation carried out a mass retaliatory strike overnight using precision sea-based weapons against facilities where terrorist acts against the Russian Federation were being prepared using uncrewed boats," the ministry said in a statement.

It said it had struck a ship repair plant near Odesa where such boats - thought to be naval drones of the kind Russia believes were used to attack the Crimean bridge - were being built.

"In addition, storage facilities holding around 70,000 tons of fuel used to supply the Ukrainian military's equipment were destroyed" near the cities of Mykolaiv and Odesa, it said.

It said all the targets had been struck and destroyed, citing fires and detonations as evidence.

Reuters could not independently confirm the account.

Ukraine's air force said earlier that six Kalibr cruise missiles and 31 out of 36 drones had been shot down, mostly over the coastal Odesa and Mykolaiv regions in the south.

A Russian couple was killed and their 14-year-old daughter wounded on Monday in what Moscow said was a Ukrainian attack that knocked out the road part of the bridge linking Russia to Crimea, which Moscow annexed from Ukraine in 2014.

Kyiv has not claimed responsibility for the attack.

Ukrainian media said Ukrainian security services had used naval drones to attack the bridge, which had only recently returned to full operation after suffering severe damage in a similar attack last October.

Kremlin spokesman Dmitry Peskov said on Tuesday it had been clear to Moscow from the start that Ukraine was behind the attack, which prompted some Russian tourists to flee Crimea by driving through parts of southern Ukraine controlled by Russian forces.

Peskov confirmed that the overnight strikes had been revenge for the bridge attack.

Alexander Kots, a high-profile Russian war correspondent for the Komsomolskaya Pravda newspaper, praised Moscow's decision to strike Ukraine's port infrastructure, but questioned why such strikes had not been launched preemptively.

"Why was the shipyard near Odesa, where marine drones are manufactured, hit in response and not preemptively? Was the intelligence received only after the strikes on the bridge?" Kots asked on social media.

He noted that Ukraine has used naval drones more than once to try to attack Russia's Black Sea Fleet, which is based in the Crimean port of Sevastopol, raising more questions about why the drone site was not targeted earlier.

"(And) why were the oil storage facilities hit in retaliation rather than as part of a planned effort to destroy the enemy's military infrastructure?" Kots asked. "It (Ukraine), for example, does not need any excuse to do this systematically. It does it (hits Russian military infrastructure) without hesitation."

(Reporting by Reuters; Writing by Andrew Osborn; Editing by Conor Humphries and Mike Harrison)