The first deputy leader of the Batkivschyna Party, Oleksandr Turchynov, has called for mass rallies to support
former Ukrainian Premier Yulia Tymoshenko.
"Let's start mobilizing," he said.
According to him, if enough people start active protests
then in September Ukraine could have a new government.
"There are many sympathizers, but not so many people that are ready to fight. We're starting an active fight today," Turchynov said.
Yulia Tymoshenko, on trial for abusing her authority in reaching a 2009 gas deal with Russia when she was Ukraine's prime minister, was arrested today on contempt-of-court charges.
One of her assistants said she was taken to the Lukyanivska pre-trial detention center in Kyiv.
Court hearings on the Russian gas supply contract case will continue at 10.00 on August 8.