KIEV, Dec. 20 – Former Prime Minister Yulia Tymoshenko was charged on Monday with abuse of power while in the government for allegedly misusing funds raised from selling carbon dioxide emission allowances in 2009.

Prosecutors allege that Tymoshenko diverted some of 320 million euros raised from selling the allowances in 2009 towards paying out pensions and social security payments.

The charges represent the biggest legal challenge for Tymoshenko, the leader of the largest opposition party in Ukraine, since she was ousted as the prime minister in March.

Tymoshenko, speaking to reporters after an interrogation by the prosecutors on Monday, said the charges are politically motivated and aimed at destroying the opposition to President Viktor Yanukovych.

“This all looks like an absurd,” Tymoshenko said. “By doing so, the president of Ukraine has been settling accounts with his main rival.”

The charges come days after a criminal investigation has been opened, and the high pace of investigation shows that the Prosecutor General’s Office has been moving fast against Tymoshenko.

The prosecutors also restricted Tymoshenko’s ability to travel, effectively disrupting her plans to visit Brussels over the weekend for a summit of the European People’s Party.