The United States tried Thursday to defuse a potential row with its European allies after the leak of an embarrassing phone call in which a top US diplomat cursed the EU response to the Ukraine crisis.
The leak of the bugged conversation came as Ukraine's embattled president, Viktor Yanukovych, flew to Sochi, Russia late Thursday for crisis talks with Russian counterpart and ally Vladimir Putin on the sidelines of the opening ceremony for the Winter Olympics.
Washington and Brussels have engaged in a diplomatic standoff with Kiev and Moscow over mass pro-EU protests that erupted in Ukraine when Yanukovych in November rejected a pact with the EU under Russian pressure.
But the leaked phone call appears to reveal US frustration with the EU over handling Ukraine, which is torn between leaning to the European Union and its past master Russia.
Washington's new top diplomat for Europe, Victoria Nuland, apologised Thursday to EU counterparts after she was caught cursing the European response to the crisis in Kiev.
"Fuck the EU," Nuland allegedly says in what appeared to be a recent phone call with US ambassador to Kiev, Geoff Pyatt, which was somehow intercepted and uploaded onto YouTube accompanied by Russian captions.
US officials, while not denying such a conversation took place, refused to go into details, and pointed the finger at Russia for allegedly bugging the diplomats' phones.
"Let me convey that she has been in contact with her EU counterparts, and of course has apologized," State Department spokeswoman Jen Psaki said.
While Psaki said she had no independent details of how the conversation was captured and uploaded onto the social networking site, she added: "Certainly we think this is a new low in Russian tradecraft."
Nuland, who took over late last year as assistant secretary for European affairs, and Pyatt appear to discuss Yanukovych's offer last month to make opposition leader Arseniy Yatsenyuk the new prime minister and Vitaly Klitschko deputy prime minister. Both men turned the offer down.
Nuland, who in December went down to Independence Square in Kiev in a show of support for the demonstrators, adds she has also been told that the UN chief Ban Ki-moon is about to appoint a former Dutch ambassador to Kiev, Robert Serry, as his representative to Ukraine.
"That would be great I think to help glue this thing and have the UN glue it and you know, fuck the EU," she says.
Yanukovych, following talks with Nuland, left Kiev for Russia's Black Sea city of Sochi, where he was expected to discuss a critical bailout deal for his crisis-hit country.
"He has arrived," a source familiar with the situation told AFP ahead of Friday's opening ceremony for the Winter Olympic Games. "The talks (with Putin) can happen any time now."
In December, Putin promised Yanukovych the $15 billion bailout but said last week the financing would not be released in full until the formation of a new government in Kiev.
The protesters earned concessions from Yanukovych -- notably the dismissal of the government and the scrapping of controversial anti-protest laws.
The Kremlin on Thursday accused the United States of arming Ukranian "rebels" and warned Russia could intervene to end the crisis.
"The stunts the Americans are pulling today by crudely interfering in Ukraine's domestic affairs in a unilateral manner are an obvious violation" of a 1994 treaty giving the US and Russia roles as security co-guarantors for Ukraine, Sergei Glazyev, Putin's economic adviser, told the Ukrainian edition of Russia's Kommersant.
When conflicts arise, the guarantors "are obliged to intervene," Glazyev said.
The hawkish adviser, who is viewed as the Kremlin pointman on Ukraine, added: "According to our information, American sources spend $20 million a week on financing the opposition and rebels, including on weapons."
He alleged that militants were briefed in the US embassy and being armed.
A Ukrainian activist who had been abducted in Ukraine last month told reporters the Lithuanian capital Vilnius that he had been "crucified" to a wooden door, and beaten until he was made to say he was an American spy.
"I told them that the American ambassador had given me $50,000," Dmytro Bulatov said in a hospital where he is undergoing treatment. "It was so scary, it was so painful that I asked them to kill me. I lied because I could not stand the pain."
The US embassy did not immediately comment on Glazyev's allegations, referring all questions to Nuland.
The US diplomat's visit came a day after EU foreign affairs chief Catherine Ashton said in Kiev that Yanukovych's government was not doing enough to overcome Ukraine's worst crisis since independence in 1991.
After the meeting with Nuland, Yanukovych's office said the president supported swift constitutional reforms backed by protest leaders that would curb some of his powers.
But both the opposition and the West suspect the 63-year-old leader is playing for time.