VIENNA/KYIV: In his years as the chief executive of one of Ukraine's biggest construction firms, Oleh Maiboroda kept rolls of dollar bills in a safe behind his desk.

The money, Maiboroda told Reuters, was intended to bribe public officials to approve building projects. The task of handing over the cash, he said, was entrusted to a lawyer named Oleh Tatarov, now a senior adviser to Ukraine's president Volodymyr Zelenskyy.

"Tatarov used to solve all issues with law enforcement," Maiboroda said in an interview in Vienna, where he has settled to escape prosecution in Ukraine for his own alleged role in corruption schemes involving the construction firm, Ukrbud Development.

Maiboroda said bribes flowed through Tatarov from 2014 to 2019. The lawyer's contacts with police, courts and prosecutors made him a perfect go-between. "Of course he was paying" to smooth projects with authorities, including by securing building permits, Maiboroda said. "He was giving them money so these arrangements were done," he added.

Maiboroda's remarks threaten to reignite a controversy that has plagued President Volodymyr Zelenskyy even in wartime: Accusations by political opponents and anti-corruption campaigners that powerful people have shielded Tatarov from prosecution.

Maiboroda provided no proof of his accusations. They echo an allegation against Tatarov, levelled by Ukraine's anti-corruption agencies, that he organised a bribe. Prosecutors closed the case in April 2022 on procedural grounds.

Tatarov, the president's adviser on law enforcement and security agencies since 2020, has denied wrongdoing and has been convicted of no crime. He has said his accusers are trying to settle political scores. Zelenskyy has previously said corruption has no place in his administration.

"I want to emphasise: If those who work with me are suspected of corruption, these people will be fired. And I have not yet seen such examples in my Office," he said in an interview in December 2020 with Ukraine's Focus magazine.

Neither Zelenskyy nor Tatarov responded to detailed questions for this article.

Zelenskyy has been lauded as a wartime leader since Russia began its full-scale invasion in February last year. S...