Ukraine on Wednesday said it had restarted operations at its blockaded Black Sea ports as it moved closer to resuming grain exports with the opening of a coordination centre to oversee a UN-backed deal.
Progress towards fulfilling the landmark agreement came as Kyiv's artillery struck a key bridge in Moscow-controlled territory in south Ukraine, damaging an important supply route as Ukrainian forces look to wrest back the Kherson region.
German authorities said Russia's state giant Gazprom drastically cut gas deliveries to Europe via the Nord Stream pipeline to about 20 percent of capacity in a move decried in the EU as revenge for Western sanctions over the invasion.
Ukraine and Russia last week agreed a plan with the help of Turkey and the United Nations to allow grain stranded by Moscow's naval blockade to be exported from three ports.
Kyiv has said it hopes to begin sending out the first of millions of tonnes of grain "this week" despite a missile strike by Russia over the weekend on the port in Odessa.
Ukraine's navy said "work has resumed" at the export hubs to prepare for ships to be escorted through the mine-infested waters to reach world markets.
As part of the deal, a coordination centre involving Ukrainian and Russian representatives opened in Istanbul to monitor the safe passage for shipping along established routes and oversee inspections for banned weapons.
The blockage of deliveries from two of the world's biggest grain exporters has contributed to a spike in prices that has made food imports prohibitively expensive for some of the world's poorest countries.
- 'Leave Kherson' -
Fighting has continued to rage on the ground in Ukraine despite the push to get the grain out, and Kyiv struck back by hitting the vital Antonivskiy bridge over the Dnipro river in a move that threatens to cut supply lines to Russian troops.
Kirill Stremousov, the deputy head of the Russian-installed regional administration in Kherson, confirmed the bridge had been hit overnight and traffic had been halted.
But he sought to downplay the damage, insisting that the attack would not affect the outcome of the hostilities "in any way."
Ukrainian forces in recent weeks have been clawing back territory in the Kherson region, which fell to Russian forces easily and early after their invasion launched on February 24.
Their counter-offensive supported by Western-supplied long-range artillery has seen its forces push closer to Kherson city, which had a pre-war population of under 300,000 people.
Russian forces "should leave Kherson while it is still possible. There may not be a third warning," Ukrainian presidential advisor Mykhaylo Podolyak said on Twitter after the attack.
In the bludgeoned Donetsk region to the east -- a key focus of Russia's war -- AFP journalists saw a house hit in an intense artillery exchange around the ravaged frontline city of Bakhmut.
A worker was inside the courtyard when the shell hit and he was saved by emergency rescuers who cut a hole in a steel fence using an axe.
"I heard a whistle. And I don't remember anything. It exploded and I was thrown into the barn by the explosion," 51-year-old Roman told AFP.
Ukraine's emergency services said that Russian artillery had hit a hotel in Bakhmut, leaving two people dead and three injured.
- Gas 'power play' -
Deepening an energy crisis in Europe sparked by the war, Germany's energy regulator said gas flows via the key Nord Stream pipeline had dropped to 20 percent of capacity on Wednesday from 40 percent.
EU states have rejected Gazprom's claims of technical problems and accuse the Kremlin of squeezing supplies in retaliation for Western sanctions over Moscow's war in Ukraine.
Kremlin spokesman Dmitry Peskov blamed EU sanctions for the limited supply.
"Technical pumping capacities are down, more restricted. Why? Because the process of maintaining technical devices is made extremely difficult by the sanctions adopted by Europe," Peskov said.
But Berlin has dismissed the explanation and government spokeswoman Christiane Hoffmann called the reductions a "power play" by Moscow.
The European Union has been bracing for the cutbacks and on Tuesday agreed a plan to reduce gas consumption by 15 percent this winter to break its dependence on Russia.