By Natalia Zinets and Matthias Williams
KIEV (Reuters) - Ukraine's infrastructure minister, who shepherded the entry of low-cost carrier Ryanair into the country this year, is under investigation by anti-corruption detectives on suspicion of illegal enrichment, national investigators said.
It is the highest-profile case since the national anti-corruption bureau (NABU) was set up after street protests in 2014 brought a pro-Western government to power promising to root out graft and enact reforms.
In a Facebook post on Thursday, Infrastructure Minister Volodymyr Omelyan denied any wrongdoing. He suggested the investigation could be a way of discrediting him ahead of elections next year and that he had been targeted by vested interests for pushing economic reforms.
NABU detectives notified Omelyan of the investigation on Thursday morning, alleging that his assets, which included $90,000 in cash and a BMW car, exceeded what he would have earned as a civil servant since the year 2000.
They also allege that he did not declare assets worth hundreds of thousands of dollars across 2015 and 2016, including a BMW, the cost of renting the home that he lived in, and the cost of a country residence and land that he also used.
"The issue of choosing precautionary measures is being considered now," NABU, whose investigators were trained by the U.S. FBI, said in a statement.
NABU and prosecutors have called on Omelyan to pay a 5 million hryvnia ($177,872) bond pending the outcome of the case, and a court will decide whether to approve the request.
Omelyan had told Reuters in an interview in March that he expected legal cases to open against him because he is helping drive reforms, which aim to liberalise the ex-Soviet republic's economy, purge corruption and improve governance.
"But it's normal. It's Ukraine. It's my headache," he said at the time.
Omelyan returned to the theme in his Facebook post, saying criminal proceedings could be opened against people carrying out reforms "because we live at a time when everything is acquired through struggle."
"The elections have started," he added. Ukraine goes to the polls in presidential and parliamentary elections next year.
Omelyan helped bring Ryanair to Ukraine in March, something the government hailed as a showcase example of Kiev making life easier for foreign investors despite the country's problems of corruption and the influence of oligarchs over the economy.
His office declined further comment when contacted by Reuters on Thursday, but he was to hold a press conference at 1430 GMT.
(Additional reporting by Olena Vasina; Editing by Mark Heinrich)