Former Prime Minister Yulia Tymoshenko, who leads the influential Batkivshchyna – or All-Ukrainian Union “Fatherland” party – made the announcement in parliament on Tuesday, accusing the president of involvement in criminal activity.
The move came a day after BIHUS.info, a Kiev-based investigative journalism unit, released the first two parts of a four-part report that implicated Poroshenko in a money laundering scandal involving top defence officials.
“We believe that what was done and what was disclosed by investigative journalists fall under Article 111 of the Criminal Code of Ukraine State treason,” Tymoshenko said.
The BIHUS report revealed that “top officials of the defense industry” were receiving kickbacks for obtaining contraband military vehicle parts at inflated prices.
More controversially, many of those parts appear to have been smuggled in from Russia, according to the report.
The report named Oleh Hladkovskyi, a member of Ukraine’s National Security Council and a close friend of Poroshenko, as one of those involved in the scheme, as well as Hladkovskyi’s son.
While Poroshenko has not been accused of direct involvement in the scheme, MPs and BIHUS have said he likely ignored the scheme to protect Hladkovskyi.
The president is yet to comment on the investigation or the impeachment proceedings, focusing instead on his campaign and events to mark the fifth anniversary of the Russian annexation of Crimea.
On Tuesday, Poroshenko met Kurt Volker, the United States special representative for Ukraine.
The growing scandal comes as Ukraine gears up for the presidential election on March 31.
A record 44 candidates are set to compete for the country’s top seat, with recent polls showing comic actor Volodymyr Zelenskiy in the lead.
Poroshenko, who came to power in 2014, following waves of protests against then-President Viktor Yanukovich, is seeking re-election, though his prospects are expected to suffer as a result of the scandal.