KIEV, Dec. 30 – Yulia Tymoshenko, the leader of the largest opposition party in Ukraine, was interrogated for more than 11 hours on Thursday as the authorities scramble to press ahead with charges against her.

The interrogation, without even a short break, was almost twice as long as the questioning on Wednesday that had been carried out without the presence of her lawyer.

The developments underscore a mounting pressure on the opposition leader that Tymoshenko said had been ordered by her political opponent, President Viktor Yanukovych.

The pressure comes despite a specific warning from the U.S. government on Thursday that the latest investigations against opposition figures in Ukraine may be politically motivated.

“We have raised with the Ukrainian government our concern that while corruption should be pursued, prosecution should not be selective or politically motivated,” the U.S. government said in a statement.

“In that context, we also raised our concern that when, with few exceptions, the only senior officials being targeted are connected with the previous government, it gives the appearance of selective prosecution of political opponents,” the statement said.

The U.S. government issued the statement reacting to an overwhelming number of arrests and investigations against opposition figures in Ukraine over the past several months.

It shows the level of attention that foreign governments are paying to the developments, and may indicate possible repercussions if the authorities continue to target the opposition groups.

Tymoshenko showed up at the Prosecutor General’s Office at noon on Thursday, and spent more than 11 hours at the office before she had been released, according to Maryna Soroka, Tymoshenko’s spokeswoman.

“She did not have a breakfast, she did not have a lunch, she did not have a dinner,” Soroka said.

The prosecutors demanded that Tymoshenko again show up at the office on Friday – the New Year’s Eve – for an interrogation that may continue well into the New Year.

Tymoshenko, a former prime minister, is charged with misspending some funds raised from selling carbon dioxide emission allowances in 2009 towards paying out pensions and social security payments.

The interrogations seem to intensify after Tymoshenko had suggested she will seek to visit Brussels next month for “discussions” with European leaders over deteriorating level of democracy in Ukraine under Yanukovych.

This may slow down plans by the Yanukovych administration to signing an association agreement between Ukraine and the European Union.

There are 18 separate investigations underway against various opposition figures in Ukraine that represent the government of then Prime Minister Tymoshenko, according to Prosecutor General Viktor Pshonka.

Most recently, Yuriy Lutsenko, a former interior minister and an ally of Tymoshenko, was arrested on Sunday and will be held behind bars for two months until his case is submitted to court.

Lutsenko joins at least five other senior officials and Tymoshenko allies already arrested by the law enforcement agencies over the past several months.

Hanna Herman, a deputy chief of staff at the Yanukovych administration, said Thursday the latest investigations were not politically motivated.

“If a person has violated the law, he must understand that sooner or later he will be held accountable,” Herman said. “That’s because when the next government comes and conducts an audit of our activity, anyone breaking the law will be held accountable.”

“So, the European politicians must too get used to the idea that Ukraine will stick to the law,” Herman said. “Everyone will be held accountable according to the law. There will be no more double standards.”

“Liberty and democracy means accountability,” she said. (tl/ez)