Supplies via Nord Stream 1, which runs under the Baltic Sea to Germany, were halted for maintenance on July 11 but, even before that outage, flows had been cut to 40 percent of the pipeline's capacity in a dispute prompted by Russia's invasion of Ukraine.

Thursday's flows were back at that 40 percent capacity level, Nord Stream figures showed.

The supply disruptions have hampered European efforts to refill gas storage for winter, raising the risk of rationing and another hit to fragile economic growth if Moscow further limits flows in retaliation for Western sanctions over war in Ukraine.

"We are in process of resuming gas transportation. It can take few hours to reach the nominated transport volumes," a spokesperson for the pipeline operator told Reuters earlier.

Physical flows were at 29,289,682 kilowatt hour/hour between 7 a.m. and 8 a.m., the Nord Stream 1 website showed, returning to pre-maintenance level of flows.

Klaus Mueller, president of Germany's network regulator, said the resumption of flows back to 40 percent capacity was not a sign tensions were easing. "The political uncertainty and the 60 percent cut from mid-June unfortunately remain," he said on Twitter.

Gazprom, which has a monopoly on Russian gas exports by pipeline, did not respond to a request for comment.

To try to prevent a winter supply crunch, the European Commission has proposed a voluntary target for all EU states to cut gas use by 15 percent from August to March compared with usage in the same period of 2016-2021. The commission proposal would enable Brussels to make the target mandatory in a supply emergency.

‘Energy as a weapon’

"Russia is blackmailing us. Russia is using energy as a weapon," EU Commission President Ursula von der Leyen said on Wednesday, adding that Europe had to prepare for the worst now.

The Kremlin says Russia is a reliable energy supplier and blames sanctions for reduced flows.

Kremlin-controlled Gazprom had cut gas exports via the route in June to 40 percent of capacity, blaming sanctions for delaying the return of a pipeline turbine that Siemens Energy was servicing in Canada.

That turbine was reported this week to be on its way back, but Gazprom said on Wednesday it had not received documentation to reinstall it and said the return of the turbine and maintenance of other gear was needed to keep the pipeline running safely.

Putin added to Europe's concerns about supplies via Nord Stream 1 by saying on Wednesday that flows could be reduced further or stopped because the quality of serviced equipment could not be assured and saying other gear needed maintenance.

A spokesperson for Austria's OMV said Gazprom had signaled it would deliver around half the agreed gas volumes on Thursday.

Italy's ENI said it would receive about 36 million cubic meters (mcm) per day of gas from Gazprom, up from average volumes of the last 10 days during Nord Stream 1 maintenance of about 21 mcm/day and back near pre-maintenance levels.

European states have been chasing alternative supplies, although the global gas market was stretched even before the Ukraine crisis, with demand for the fuel recovering from the pandemic-induced downturn.