Ukraine on Tuesday opened a probe into possible abuse of power by Yuriy Lutsenko, the former prosecutor who figures in the whistleblower complaint against US President Donald Trump.
Lutsenko, who was fired from his post of prosecutor general in August, is suspected of "abetting illegal gambling business," the spokeswoman of Ukraine's State Bureau of Investigations Anzhelika Ivanova told AFP.
The investigation was launched at the request of Ukrainian lawmakers, she said, without elaborating on the exact allegations.
Ukrainian news agency Interfax reported that the probe started after a statement given by David Arakhamia, a senior MP with the party of President Volodymyr Zelensky.
The statement has not been made public but Lutsenko, who is currently in London, denied the allegations.
"One must have great imagination to accuse me of what Mr. Arakhamia is saying," Lutsenko said on his Facebook page.
Last week Lutsenko wrote that the complaint against him for abuse of power made by a security services employee was "manipulative and untrue".
Meanwhile the US whistleblower complaint published last week claimed Trump attempted to advance his personal interest in a call with Zelensky in July, during which he praised Lutsenko as a good prosecutor and suggested he keep his position.
Trump and his allies claim that former US vice president Joe Biden, his potential rival in the 2020 presidential race, pressured Kiev to fire a previous prosecutor Viktor Shokin in 2015-16 to protect his son Hunter, who sat on the board of Burisma, a gas company accused of corruption.
EU countries and the International Monetary Fund had also called for Shokin to be removed.
Lutsenko has said that he met with Trump's lawyer Rudi Giuliani over the matter, but that ultimately there was no reason to investigate Biden and his son under Ukrainian law.
The whistleblower complaint says earlier this year Lutsenko had made allegations regarding activities of Biden's family in Ukraine, and claimed that former US ambassador Marie Yovanovich obstructed Ukrainian law enforcement.
The claims have been echoed by Trump's allies, and Yovanovich was recalled from her post in May. She has now been summoned to be questioned by US congressional committees in the impeachment inquiry against Trump.