Svyatoslav Piskun, who was the country's prosecutor general until last Friday, claimed he had been fired because he opened an inquiry into allegations that Mr Yushchenko's US-born wife had flown a group of her relatives to Kiev from the US on a specially chartered plane for her husband's inauguration as president earlier this year. Mr Piskun said the bill amounted to £155,000 and he wanted to know where the money came from, inferring that it may have been linked to a discredited Ukrainian businessman wanted for money laundering in the US.
"My dismissal was a direct consequence of my refusal to submit to political pressure," he said.
This is not the first time that Mr Yushchenko's family members have been dragged into a political row. His teenage son, Andrei, was criticised for leading a flashy lifestyle seemingly beyond his modest student means, while Kateryna was accused of working on behalf of the US government, allegations she has quashed in court.
Mr Yushchenko and his allies dismiss Mr Piskun's claims saying he was sacked for incompetence. The main reason, they say, was his failure to wind up a politically explosive investigation into the killing of the investigative journalist Georgy Gongadze in 2000.
Mr Yushchenko's credibility has come to rest on the case's successful prosecution. A parliamentary committee accused Leonid Kuchma, Mr Yushchenko's predecessor, of ordering the abduction but Mr Kuchma has been left alone.Reuse content