BRUSSELS, Jan. 28 – Prime Minister Yulia Tymoshenko said on Monday the recent arrest in Moscow of Semion Mogilevich, the alleged leader of a criminal ring said to be tied to Russian gas-trading entity, indicates upcoming sweeping changes in natural gas trading between Ukraine and Russia.

Mogilevich has long been alleged of having a link, through Dmytro Firtash, a Ukrainian businessman, to RosUkrEnergo, a Swiss-based gas trader now controlled by Gazprom of Russia.