Ukrainian President Viktor Yanukovych said on Thursday he could not pardon jailed opposition leader Yulia Tymoshenko despite the early release from jail of one of her top allies.
"I have answered this question on repeated occasions," the former Soviet republic's leader told reporters.
"Until the court hearings into Tymoshenko are over, it is impossible to review the issue of a pardon."
The Ukrainian leadership won rare praise from the European Union and the United States for its decision earlier this month to pardon six people, including top Tymoshenko ally Yuriy Lutsenko, the country's former interior minister.
The imprisonment of both Tymoshenko and Lutsenko has drawn strong criticism from the United States while EU leaders have refused to sign an important trade agreement with Kiev until they were released.
Lutsenko was arrested while walking his dog in Kiev in 2010 and had been sentenced to remain in prison until the end of 2014 after being convicted of abuse of office and embezzlement.
The pardon came after Ukraine's high court rejected Lutsenko's appeal.
Tymoshenko, who lost a heated presidential election to Yanukovych in 2010, was jailed for seven years in 2011 on charges of overstepping her authority while prime minister by agreeing a gas deal with Russia.
She is currently on trial on separate charges of fraud and tax evasion and was also accused in January of ordering the 1996 gangland murder of lawmaker Yevgen Shcherban.