The Batkivschyna United Opposition has demanded that Ukrainian officials involved in the scam with the purchase of the so-called "Boiko rigs" (sea gas drilling rigs, which, according to the opposition, have been illegally privatized by Energy and Coal Industry Minister Yuriy Boiko) should be questioned either by Ukrainian or European law enforcement agencies.

"We are demanding that law enforcement agencies, first and foremost, Ukraine's prosecutor general, provide an opportunity for Latvian law enforcement officers to question all those involved in the scam from the Ukrainian side, so that they are brought to account," a leader of the united opposition, Anatoliy Hrytsenko, said at a press conference on Thursday, while commenting on the fact that Latvian law enforcement agencies launched a criminal investigation against a company that participated in the purchase of drilling rigs for gas extraction in the Black Sea and that the company's accounts were frozen.

However, he declined to name Ukrainian officials as part of this investigation.

"The criminal case was opened in Latvia. This is their responsibility, and they determine whom they need to question. I can assume that these will be representatives of the Chornomornaftogaz state-owned company and national JSC Naftogaz Ukrainy," Hrytsenko said.

At the same time, the MP said he was confident that Latvian law enforcers would complete the investigation into this case.

"We're talking about the activity or inactivity of officials or their political responsibility for the obvious facts of corruption in Ukraine. The names are obvious here. Firstly, does President [Viktor] Yanukovych know about this criminal scam? Yes, he does know. Did former SBU Chief Valeriy Khoroshkovsky know about that? Yes, he did know," he said.

Hrytsenko also said that the leadership of the Accounting Chamber, the Chief Financial Inspectorate of Ukraine and the Prosecutor General's Office was aware of this deal.

"When these people are not taking respective measures to investigate these facts, they are becoming accomplices in this crime," he said.

He said that all of these officials would be responsible for their actions, if not now, then after the presidential elections in 2015.

Hrytsenko also noted that similar actions in any European country would lead to the dismissal of officials involved in such a scam.

Batkivschyna Party member Ostap Semerak, in turn, also said that he had investigated this case for one-and-a-half years and that he had all of the materials and documented evidence of such a scam related to the purchase of drilling rigs.

He said that the list of people whom Latvian law enforcement officers would like to question was the secrecy of the investigation.

"The only thing I know from my contact with an investigator is that Ukrainian law enforcement agencies don't want to cooperate with investigators," he said.