Operations have resumed at the Ukrainian Black Sea port of Odesa after Russia used Iranian-made drones to hit energy facilities in the city.
The port in the south of the country was closed after strikes on Saturday left 1.5 million people and all non-critical infrastructure without power.
Ukraine’s president said it could take days to restore electricity, with sub-zero temperatures expected this week.
Odesa is one of three ports being used to ship grain under a UN-brokered deal.
The agreement, mediated by Turkey and the UN, allows Ukrainian products to be transported safely to the rest of the world. The deal has helped bring down soaring global food prices.
Although operations at Odesa port were briefly stopped on Sunday, Ukraine’s agriculture minister said grain exports would not be suspended.
In total, Russia launched 15 Iranian-made drones at the regions of Odesa and neighbouring Mykolaiv, 10 of which were shot down, Ukraine’s armed forces said.
“The situation in the Odesa region is very difficult,” Ukraine’s President Volodymyr Zelensky said in his nightly address. “Unfortunately the hits were critical, so it takes more than just time to restore electricity. It doesn’t take hours, but a few days.”
Thousands of people have made use of the region’s “points of invincibility” – facilities which supply electricity and warmth to residents during blackouts.
Images posted on social media showed dozens of people crowding round power points charging their phones.
The strikes on Ukraine’s energy infrastructure, which intensified in mid-October, have left millions of people in nearly all regions of the country without power, as temperatures drop below zero.
A complete blackout across the entire country is a now realistic scenario, Ukraine’s Foreign Minister Dmytro Kuleba told German television on Sunday.
Russia’s frequent attacks on Ukraine’s power grid have led to calls for the West to supply Kyiv with better air defence weapons.
On Sunday, US President Joe Biden told President Zelensky that Ukraine’s air defence was a priority for Washington.
The two spoke in a phone call before a meeting of G7 leaders on Monday, where further sanctions against Russia and Iran will be discussed.
The proposed measures would target Iran over its supply of drones to Russia, while EU foreign ministers are set to discuss a ninth package of sanctions which would place almost 200 more individuals and entities on its sanctions list.
East of Odesa, Ukrainian strikes killed two people in the Russian-occupied city of Melitopol over the weekend, according to Moscow-installed local authorities.
The city has been under occupation since early March and is a major logistics hub for Russian forces in the south-east.
It is strategically located between Mariupol to the east, Kherson and the Dnipro River to the west, and Crimea to the south.