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, BBC reported. 

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.