KIEV, Ukraine -- Ukraine's president has told U.S. Vice President Joe Biden that he wants American investors to help modernize its strategic gas transport system at a time of a severe economic crisis.

Ukraine's aging gas transit infrastructure carries gas from Russia to Europe. President Viktor Yushchenko told the visiting Biden that "as many investors as possible, including U.S. investors" could help ensure the continent's energy security.

A January dispute over natural gas prices with Moscow left millions in Europe without heating gas for two weeks after Russia cut off its energy exports through Ukraine.

Ukraine has also turned to the EU and Russia to fund the upgrade.