Two trading sources told Reuters news agency the Russian oil transit to Europe via Belarus was so far continuing uninterrupted.

Europe receives about 10 percent of its oil via the transit link, known as the Druzhba pipeline, which can supply more than one million barrels per day to countries including Germany, Poland, Slovakia, Hungary and the Czech Republic.

Moscow and Minsk have had several oil and gas spats over the past 10 years, in what has been described as a love-hate relationship between presidents Vladimir Putin and Alexander Lukashenko.

Putin and Lukashenko have repeatedly toyed with the idea of political integration of the countries, but the Belarusian leader who came to power in 1994 has backtracked repeatedly.

Deliveries have been suspended ... Plants are reducing their workload to the technical minimum

Belneftekhim spokesman

Russia has cut subsidies to Belarus over many years and is now charging close to international prices for oil and gas, but contracts negotiations are often protracted.

"Deliveries have been suspended ... Plants are reducing their workload to the technical minimum," said a spokesman for Belneftekhim, known in English as the Belarusian State Concern for Oil and Chemistry.

Russian pipeline operator Transneft also said Russian oil companies had not sent any oil to Belarus this year, the TASS news agency reported.

"Since January 1, we have not had any applications from oil companies to deliver to Belarusian refineries. However, oil transit through Belarus is continuing in full volumes," Transneft spokesman Igor Dyomin was cited as saying.

It was not clear when Moscow and Minsk could resume talks on their 2020 contract. Russia is on a long New Year holiday until January 9.