Ukrainian drones hit St Petersburg as Putin's flagship economic forum opens

Ukraine has carried out a strike on the outskirts of Russia's St Petersburg, hours before the opening of a major economic forum designed to attract foreign investment into the country.

As dawn broke black plumes of smoke rose over Russia's second city, where Vladimir Putin is due to address the financial event on Friday. Thousands of guests from 130 countries are due to attend, including a low-key US delegation.

Local authorities said air defences shot down 59 drones overnight and that three different districts of St Petersburg had been hit, although no one was killed.

Kremlin spokesman Dmitry Peskov said Moscow would respond to the strikes. "Our responses will be systemic in nature," he said on Wednesday.

Mobile internet was disrupted and St Petersburg's Pulkovo Airport was temporarily closed, while some regions of nearby Latvia and Estonia also issued air raid alerts.

Hours later, Volodymyr Zelensky confirmed Ukrainian drones had hit several locations in Russia, including the oil terminal and a naval base in the nearby town of Kronstadt.

"The Ukrainian plan of long-range sanctions is being implemented exactly as it is needed to bring peace closer," Zelensky wrote on social media, using a euphemism for long-distance strikes on Russia.

Kronstadt is the main outpost of the Russian Navy's Baltic Fleet. Unverified videos posted on social media by Ukrainian military figures showed drones heading for docked military ships, with the video cutting off before impact.