The EU refused to be drawn Friday on controversial remarks by a senior US diplomat about its efforts to help resolve the Ukraine crisis.

"We don't comment on leaked alleged telephone conversations," said a spokeswoman for EU foreign affairs head Catherine Ashton.

The European Union "is engaged in helping the people of Ukraine through the current political crisis," the spokeswoman added.

The spokeswoman declined further comment.

Washington's top diplomat for Europe, Victoria Nuland, apologized to her EU counterparts Thursday after a leaked phone call had her cursing the European response.

"Fuck the EU," Nuland allegedly says in what appeared to be a recent phone call with U.S. ambassador to Kiev, Geoff Pyatt.

The call appears to have been intercepted and uploaded onto YouTube accompanied by Russian captions.

U.S. 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.

Nuland, who took over late last year as assistant secretary for European affairs, and Pyatt appeared to be discussing President Viktor 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.

"That would be great I think to help glue this thing and have the U.N. glue it and you know, fuck the EU," Nuland says, in apparent frustration at policy differences.