(CNN) Ukraine will review previous investigations into the owner of an energy company linked to the son of former US Vice President Joe Biden, the country's prosecutor general announced Friday.
Ruslan Riaboshapka said his office was reviewing a number of cases opened by previous prosecutors, including probes into the owner of Burisma Holdings, a Ukrainian natural gas company that Hunter Biden once sat on the board of.
US President Donald Trump pressured Ukrainian leader Volodymyr Zelensky to investigate both Bidens during a phone call on July 25, setting off an impeachment inquiry into whether Trump abused the power of his office in order to damage a political rival.
"We are reviewing all cases opened by the previous prosecutor's office," Riaboshapka said when asked specifically about Burisma on Friday. "We will conduct an audit of previous cases including the one you mentioned."
Hunter Biden sat on the board of directors at Burisma from May 2014 until April 2019. Trump has claimed, without offering proof, that Joe Biden tried to have Ukraine's top prosecutor ousted in 2016 to stop investigations of Burisma, to benefit his son.
But the investigations did not produce any prosecutions, and there is no evidence of wrongdoing by either Biden, nor that Hunter Biden himself was ever under investigation.
Joe Biden was pushing Ukraine to fire the prosecutor general, Viktor Shokin, at the time, as were other American allies, including the International Monetary Fund and Ukrainian anti-corruption activists who said Shokin had failed to effectively investigation corruption in Ukraine.
Shokin was widely faulted for declining to bring prosecutions of elites' corruption, and he was even accused of hindering corruption investigations. His deputy, Vitaliy Kasko, resigned in February 2016, alleging that Shokin's office was itself corrupt, and Ukraine's legislature voted to fire Shokin the following month.
The announcement by the current prosecutor general, Riaboshapka, on Friday came during a news conference in which he detailed reforms to the country's prosecutor service, including the creation of a new department for high profile cases.
"We are fighting against the old system," he said. "Prosecutors should be honest and uphold the rule of law in Ukraine rather than work towards business or political requests."
This story has been updated to correct the nature and focus of investigations Ukrainian prosecutors are reviewing.