Gazprom`s CEO has warned Ukraine that delays in repaying its debt for Russian natural gas deliveries could have serious negative consequences, the Russian energy giant said on Thursday, RIA Novosti reported.

Alexei Miller spoke on Wednesday at the 19th meeting of the European Business Congress in Berlin, an international nonprofit organization formed to develop economic cooperation between OSCE countries.

"Further aggravation of this problem is fraught with serious negative consequences that must not be underestimated," said Miller, who is president of the organization.

A row over gas prices between Russia and Ukraine in the winter of 2005-2006 led to Gazprom interrupting deliveries to Ukraine, which, being a transit country, siphoned off Europe-bound supplies and caused shortages in European states.

Gazprom says Ukraine`s Naftogaz owes $2.4 billion for gas supplied in September-November, including fines and penalties, and the Russian company previously announced that supplies for next year will only be discussed once the debt has been paid in full.

Some of the funds have reportedly been repaid, but Gazprom has threatened to cut supplies if it does not receive full payment.

Ukraine, which transits about 80% of Russia`s Europe-bound gas, will have to pay $3.057 billion by the end of the year once the charge for December deliveries is included.

RIA Novosti