Ukraine faced the prospect Thursday of a fresh political crisis as its reformist economy minister resigned in protest at alleged influence-peddling and state graft.

Poroshenko held last-ditch talks with the Lithuanian-born Abromavicius Wednesday in a bid to change his mind and reassure him that all his charges would be investigated in full.

But parliament began debating the 40-year-old's future in a tense session that saw one deputy raise the prospect of holding a vote of no confidence in the government as a whole.

"It is clear to everyone that we are entering a serious political crisis," parliamentary speaker Volodymyr Groysman told reporters.

Adding to Western frustration is the fact that Abromavicius is the fourth reform-minded minister to tender his resignation since 2014 when it moved closer to Europe.

The resignations of ministers charged with putting the cash-strapped nation on a transparent path toward growth highlights the difficulties Ukraine faces in fulfilling its dream of joining the EU.

Abromavicius "was one of those leaders who put Ukraine's interests above any personal interests of his own. He did implement some important reforms," US State Department spokesperson John Kirby told a Washington briefing.

Abromavicius leveled his most serious charges against a top Poroshenko party ­member named Igor Kononenko - a ­figure the Ukrainian ­media ­often refer to as a "grey cardinal" who implements the ­president's ­political will.

He accused Kononenko of trying to push his own people into key economy ministry positions that oversee the cash flows of the vast defense and energy sectors.