Joe Biden said the US government has “strong reason” to believe the hackers behind a massive cyber attack that shut the Colonial petroleum pipeline were based in Russia, as he urged Americans to not panic over temporary fuel shortages. “We do not believe the Russian government was involved in this attack. But we do have strong reason to believe that the criminals who did the attack are living in Russia. That is where it came from,” the US president said in a speech on Thursday afternoon at the White House.

“We have been in direct communication with Moscow about the imperative for responsible countries to take decisive action against these ransomware networks,” he added, noting he hoped to discuss the issue with Russia’s president Vladimir Putin. The 5,500-mile pipeline system has capacity for 2.5m barrels a day of liquid fuels such as petrol diesel and jet fuel, which it carries from Gulf Coast refineries to major hubs in the north-east. The FBI has indicated that the shutdown was caused by a ransomware attack by hacking group DarkSide.

Cyber experts claim Russia tacitly allows ransomware gangs to operate in the country and will not prosecute them. In return, those criminals do not attack Russian companies and can be called upon to share their access to victims’ systems, experts say.

Last month, the US Treasury accused one of Russia’s intelligence services, the FSB, of “cultivating and co-opting” the notorious ransomware group Evil Corp, which has been sanctioned. The Colonial pipeline — responsible for carrying almost half of the motor fuel used on the US east coast — began the process of fully reopening on Wednesday evening, five days after it was hit by a cyber attack that triggered a spate of panic-buying by motorists across the US south-east.

Biden said the US government expected a “region by region return to normalcy beginning this weekend and continuing into next week”. He urged Americans to avoid panic-buying petrol, and said he had called on state governors and local authorities to keep a lookout for any illegal price gouging by businesses.