By Pavel Polityuk and Natalia Zinets
KIEV (Reuters) - Ukrainian state agencies sought to detain the head of the tax and customs service on Friday over the alleged embezzlement of around $75 million - a potentially landmark case after patchy anti-graft efforts from the Western-backed authorities.
Television footage showed an apparently unconscious Roman Nasirov being stretchered into an ambulance and taken to Kiev's Feofania hospital late on Thursday.
Reporters said he had suffered a heart attack. This could not be independently verified.
Anti-corruption prosecutor Nazar Kholodnytsky said investigators believe 38-year-old Nasirov helped exiled lawmaker Oleksandr Onishchenko deprive the state of 2 billion hryvnias ($75 million) in tax revenue linked to a gas deal.
"Detectives and a prosecutor went to Feofania," Kholodnytsky said on television channel 112. "Nasirov was notified of the allegation by a detective. I will find out if he was conscious or not."
Nasirov has previously denied all allegations of graft against him. His office would not immediately comment on the matter.
Prime Minister Volodymyr Groysman said Nasirov had been relieved of his duties while the case is pending. "It is in our interest that the investigation be impartial and effective. This issue is very important for Ukrainian society today," he said in a government meeting.
Prosecutor Kholodnytsky was openly skeptical about Nasirov's sudden hospitalization.
"I, like many Ukrainian citizens, have doubts about the unexpected transfer to hospital, as this has become a historic tradition for the Ukrainian political elite and top management."
He cited the example of a former transport minister who in 2008 was found by investigators in a hospital after they sought to detain him on corruption charges.
If Nasirov is found guilty, it would be the first successful prosecution of a senior official for graft since the 2014 uprising that ushered in a Western-backed leadership promising to tackle endemic corruption.
FUR COATS, JEWELS AND CASH
"This is the destruction of the unwritten corrupt status quo in the country," said pro-European lawmaker Serhiy Leshchenko in a post on Facebook.
"Nasirov will be a valuable witness to the misuse of state money by those in the highest ranks."
Stop-start reforms over the past three years have raised concerns that Ukraine's political elite lacked the will to eradicate a deep-rooted system of cronyism and bribe-taking.
Nasirov's lawyer, Andriy Kuzmenko, confirmed that he was being investigated for embezzlement and said he could face up to six years in prison.
Opposition lawmakers and the finance ministry have previously called for Nasirov to be investigated for abuse of office.
In 2016, Nasirov clashed with an activist appointed to reform the graft-plagued customs of Odessa over her accusation that he had blocked her attempts to fire corrupt officials.
In an online wealth declaration tool aimed at boosting transparency, he disclosed last October that he and his wife held cash in euros and dollars worth $2.2 million and owned Swiss watches, diamond jewelry, fur coats and fine porcelain among other items. He told Reuters in an interview he had earned this money in the financial sector before taking office.
($1 = 27.0000 hryvnias)
(Reporting by Pavel Polityuk and Natalia Zinets; Writing by Alessandra Prentice; Editing by Catherine Evans)