The beleaguered head of Ukraine`s state-owned oil and gas company resigned his post to take up a parliamentary seat, a government spokesman said Thursday, according to AP.

Oleksiy Ivchenko asked the government to relieve him of the top job at Naftogaz to take up the parliamentary seat he won in the March 26 parliamentary election, said Valentyn Mondriyevskiy. The government accepted his resignation on Thursday.

Ivchenko, who was elected as a member of President Viktor Yushchenko`s bloc, has come under constant fire for a controversial January deal with Russia that nearly doubled the price Ukraine pays for natural gas and involves a murky intermediary firm. The strong criticism directed at Ivchenko could have made his position vulnerable after the new parliament takes office and a government is formed.

Under the hard-fought gas deal with Russia, Ukraine will receive all of its imported natural gas from a little-known intermediary company, RosUkrEnergo, that is owned jointly by Russia`s OAO Gazprom and another company whose owners were not identified until last month.

Former Prime Minister Yulia Tymoshenko, who hopes to return to the premier`s job based on her party`s second-place showing in the elections - ahead of Yushchenko`s bloc - has vowed to undo the deal.

Last month, Yushchenko criticized Ivchenko for purchasing a luxury car with state funds. Ivchenko was ordered to sell the US$215,000 (euro179,000) Mercedes Benz, which he did.