MOSCOW, Nov. 20 - The Swiss trader RosUkrEnergo AG, in which Russia's Gazprom has a 50% stake, signed a three-year contract on Friday to supply gas to Polish gas monopoly PGNiG in 2007-2009.

A source in RosUkrEnergo told Interfax that, according to the document, the supplies would amount to 2.5 billion cubic meters of gas per year. This will account for about one fifth of Polish gas supplies.

The source did not say at what price PGNiG would buy the gas, and said only that it will be calculated based on a formula.