KIEV, Feb. 11 - Ukrainian oil and gas monopoly Naftogaz Ukrayiny says it will not pay a bill for $7 billion Gazprom presented in January for taking less gas than agreed under the gas supply contract between the two concerns, according to the prospectus for an issue of Ukrainian eurobonds.

"Naftogaz paid for all the gas that was actually delivered in 2012 and believes that Gazprom's bill for importing less gas than contracted is unjustified," the document says.