Ukraine strikes St Petersburg oil terminal hours before 'Putin's Davos'

A plume of black smoke is seen over the port of St Petersburg. (AP Photo)

Ukraine has struck an oil export terminal in St Petersburg hours before Russian President Vladimir Putin's annual economic forum got underway.

The governor of the wider Leningrad region said air defences had shot down 59 drones overnight.

NATO Secretary General Mark Rutte has arrived in Kyiv for an unannounced trip.

The attack on St Petersburg, Mr Putin's home city, and the location of his own 'Davos' — a showcase economic forum designed to attract foreign investment — comes as both sides dial up strikes on each other in the more than four-year-old war.

Smoke shrouds the golden dome of Saint Isaac's Cathedral in St Petersburg, Russia. (AP Photo)

A plume of smoke was visible from the historic city centre where an oil export terminal had been hit, and Reuters correspondents reported hearing loud explosions on Wednesday morning.

Ukrainian President Volodymyr Zelenskyy confirmed his drones struck the fuel terminal and said they had also targeted a military facility near what is Russia's second-largest city.

Ukraine's military also confirmed it struck a warship at Russia's Baltic Fleet base which caused a massive fire aboard the Boikiy corvette.

Banners advertise the St Petersburg International Economic Forum (SPIEF) at the forum's venue. (AFP)

Alexander Beglov, the governor of St Petersburg, said that unspecified "infrastructure objects" had been hit in three different districts of the city, damaging several facilities.

"Clean-up operations are currently underway. Several people have been injured," Mr Beglov said in a statement.

Alexander Drozdenko, governor of the wider Leningrad region, said air defences had shot down 59 drones overnight.

The Kremlin said Russia would keep striking Ukraine systematically in response to such attacks, part of what it has described as a new "paradigm" in the conflict.

Ukraine has developed AI-enabled drones capable of making precision strikes from hundreds of kilometres away, and it means using Russia's vital logistics routes has become a dangerous "lottery".

The city's Pulkovo airport had to temporarily restrict flights, Russia's aviation watchdog said, and more than 30 flights were delayed or cancelled.

Given the importance of the event to Moscow, the Ukrainian attack is likely to raise questions inside Russia about how effective its own air defence capabilities are, a problem that Ukraine is also grappling with.

The location of the economic forum itself was heavily protected, however, and there was no suggestion that Ukrainian drones