Ukraine's former Prime Minister Yulia Tymoshenko is to stand trial Friday on charges of abuse of power.
Her trial is to open at Kyiv's Pechersk court.
According to the Ukrainian Interfax news agency, representatives from the U.S. law firm Covington & Burling will make up part of the team advising Ms. Tymoshenko's defense at the criminal proceedings.
The charges stem from a 10-year natural gas import deal the former prime minister signed with Russia in 2009. Officials say Ms. Tymoshenko did not have Cabinet approval to sign the deal and exceeded her authority.
They also said the prices she agreed to were excessively expensive and cost Ukraine hundreds of millions of dollars.
Ms. Tymoshenko has also been charged with corruption in two other cases. She has maintained her innocence on all counts and says they are part of a politically motivated campaign by Ukrainian President Viktor Yanukovych to crush the opposition. Several officials who served in her government are in prison.
Mr. Yanukovych narrowly defeated Ms. Tymoshenko in presidential elections last year.