Prosecutors in Ukraine are investigating whether a member of Parliament committed treason by working with two associates of President Trump’s to promote a plan for settling Ukraine’s conflicts with Russia.
In a court filing on Tuesday, prosecutors accused the lawmaker, Andrii V. Artemenko, of conspiring with Russia to commit “subversive acts against Ukraine,” in particular by advancing a proposal that could “legitimize the temporary occupation” of the Crimean peninsula. Russia forcibly annexed the peninsula in 2014, a step that Ukraine, the United States and other governments have refused to recognize; Mr. Artemenko said his proposal would allow Ukraine to formally cede control of the territory to Russia, at least temporarily.
Yuriy Lutsenko, Ukraine’s prosecutor general, posted a copy of the court filing to his Facebook page on Tuesday with the statement “Ukraine’s integrity is above all else.”
Mr. Artemenko’s plan, reported on Sunday by The New York Times, outlines a series of steps meant to bring to an end the rebellion by Russian-backed separatists in eastern Ukraine, and to resolve the dispute over Crimea by allowing voters to decide whether to lease the peninsula to Russia for 50 or 100 years.
Settling those issues could give the Trump administration a path to lift sanctions against Russia.
Mr. Artemenko traveled to New York in January to discuss the plan with Michael D. Cohen, Mr. Trump’s personal lawyer, and with Felix H. Sater, a Russian-American business associate of the Trump Organization who scouted business opportunities in Russia for the company as recently as 2015. Mr. Cohen said he delivered the proposal to the White House in a sealed envelope in early February.
Mr. Artemenko, a little-known politician who has tried to brand himself as a Trump-style populist, has not been arrested or formally charged with a crime.
He did not immediately respond to a request for comment. The Ukrainian news outlet Strana.ua quoted him as saying that the investigation was “politically motivated.”
“I’m not going anywhere, and will meet with investigators to explain my position,” he was quoted as saying.
Mr. Artemenko has claimed he received encouragement from the Russian authorities for his effort, but the Kremlin has denied any knowledge of his proposal. He has also claimed to have evidence of corruption that could help lead to the ouster of the Ukrainian president, Petro O. Poroshenko.
The Trump administration has sent mixed signals concerning the war in Ukraine, which has cost more than 10,000 lives. White House officials have suggested that they would be open to lifting sanctions against Russia, but they have also demanded that Crimea be returned to Ukraine.
Word of Mr. Artemenko’s peace plan has prompted outrage among many officials in Ukraine. Some accused him of being a secret Russian agent, and there have been calls for him to relinquish his seat in Parliament. On Monday, fellow Radical Party lawmakers voted unanimously to expel him from the party.
The suggestion that Crimea be handed over to Russia legally, even for a limited time, particularly outraged Crimean Tatars, the ethnic group in Ukraine whose members consider the peninsula their historic homeland.
Refat Chubarov, a Tatar member of Parliament, wrote on Facebook that Mr. Artemenko should be stripped of his parliamentary immunity and arrested.
“Given the continued Russian occupation of Crimea,” he wrote, “which is characterized by the total suppression of the rights and freedoms of the Crimea Tatar people; violent kidnappings and killings of peaceful citizens; arrests of Crimean Tatar citizens and attacks on their homes and families; as well as the persecution of journalists, the actions of Andrii Artemenko are unequivocally qualified as treason.”