Two national agencies fighting corruption in Ukraine have named Ukrainian President Volodymyr Zelenskyy's former Chief of Staff as an official suspect in a major graft investigation.

Ukraine's National Anti-Corruption Bureau and the Specialised Anti-Corruption Prosecutor's Office announced late Monday (May 11) that Andriy Yermak is suspected in an alleged 460-million-hryvnia ($10.5 million) money-laundering scheme.

Investigators said in an announcement on the Telegram messaging app that the investigation is ongoing.

The move is a step short of formally charging Mr. Yermak, who resigned in November. He was the country's lead negotiator in talks with the U.S. and left during the scandal that brought the biggest threat to Mr. Zelenskyy's government since Russia's full-scale invasion.

The investigation is deeply embarrassing for the Ukrainian leader as he pushes for his country to be admitted as a member of the European Union, a process which likely will take years. Endemic corruption is one of the obstacles slowing Ukraine's admission.

Mr. Yermak was a trusted confidant of Mr. Zelenskyy, who resisted persistent pressure to replace him, and a powerful figure in the government.

Mr. Zelenskyy made no public comment on the anti-graft agencies' announcement, but his press officer, Dmytro Lytvyn, said “the investigation is ongoing, it's early to draw conclusions.”

Investigators said Yermak is suspected of being involved in laundering money through construction projects near Kyiv, the Ukrainian capital. They searched his home in November. No other suspects have been named.

A decision on whether to bring formal charges against Yermak could still take months.

At the time of Mr. Yermak's resignation, Mr. Zelenskyy said he was rebooting the presidential office and thanked Mr. Yermak for his work on peace negotiations.