The prime ministers of Ukraine and Georgia said Monday that the flow of oil in a key Ukrainian pipeline would be reversed, a decision certain to complicate the two former Soviet republics' already tense relations with Russia.

Ukrainian Prime Minister Yulia Tymoshenko and Georgian Prime Minister Zurab Nogaideli said that the Odessa-Brody pipeline would be used for oil shipments from Kazakhstan and Azerbaijan through Georgia to Western European markets, in contrast to the former government's decision to pump Russian crude through the pipeline to the Black Sea port of Odessa, said Vitaly Chepinoga, a spokesman for Tymoshenko.

Russia is Ukraine's largest trade partner and energy supplier. Key Russian pipelines and other infrastructure links with Europe run through Ukraine.

Nogaideli traveled to Ukraine on Sunday for a three-day trip and was scheduled to meet top Ukrainian officials including President Viktor Yushchenko.

It was Nogaideli's first trip abroad since filling the post left empty by the sudden death of Zurab Zhvania, who apparently suffered carbon monoxide poisoning.

Last summer, Ukraine's Cabinet agreed to open the long-idle Odessa-Brody pipeline for shipments of Russian oil to Odessa. But the United States has opposed that, saying it will increase Ukraine's energy dependence on Russia and raise chances of an oil spill as more tankers would travel through Turkey's clogged Bosporus strait.

Georgia stands to benefit from the new deal because it will earn transit fees. And Georgia, like Ukraine, is interested in expanding its self-reliance vis-a-vis the regional energy power, Russia.

Later in the day, Nogaiveli and Ukraine's new President Viktor Yushchenko discussed boosting bilateral ties, and agreed to refresh an alliance of five former Soviet republics aimed to enhance regional stability and encourage economic development.

The GUUAM group -- comprising Georgia, Ukraine, Uzbekistan, Azerbaijan and Moldova -- was established in 1997 in a bid to seek cooperation outside Russian influence.