President Joe Biden said on Saturday he has directed US intelligence agencies to investigate who was behind a sophisticated ransomware attack that hit hundreds of American businesses and led to suspicions of Russian gang involvement.

Security firm Huntress Labs said on Friday it believed the Russia-linked REvil ransomware gang was to blame for the latest ransomware outbreak. Last month, the FBI blamed the same group for paralysing meatpacker JBS SA.

Biden, on a visit to Michigan to...