KIEV, June 30 - Former Prime Minister Yulia Tymoshenko’s assets were frozen by authorities as Naftogaz Ukrayiny seeks compensation for 1.5 billion hryvnias in losses from Ukraine’s 2009 natural gas agreement with Russia, an official said Thursday.

Mykhaylo Havryliuk, deputy prosecutor general, refused to disclose the value of the frozen assets, but said law enforcement agencies have continued to search for more assets.