The European Commission is expected to propose a sixth package of EU sanctions this week against Russia over its invasion of Ukraine, including a potential embargo on buying Russian oil - a measure that would deprive Moscow of a large revenue stream, but that has so far divided EU countries.
Russia supplies 40 percent of EU gas and 26 percent of its oil imports.
To keep the 27-nation bloc united, the Commission may offer Hungary and Slovakia an exemption or a long transition period - with any overall ban likely to be phased in by the year-end, officials said on Monday.
Both Hungary and Slovakia are heavily dependent on Russian crude. Hungary has said it would oppose energy sanctions.
Resistance from other countries to an oil embargo appeared to be fading ahead of a meeting on Wednesday when ambassadors from EU countries will discuss the proposed sanctions.
"We have managed to reach a situation where Germany is able to bear an oil embargo," German economy minister Robert Habeck said on Monday. "This means it won't be without consequences."
Austrian climate and energy minister Leonore Gewessler said Vienna would agree to oil sanctions if other countries did.
EU countries have paid more than 47 billion euros (NZ$76.7 billion) to Russia for gas and oil since it invaded Ukraine on 24 February, according to research organisation the Centre for Research on Energy and Clean Air.
Photo: AFP Caption: The compressor station in Mallnow near the German-Polish border mainly receives Russian natural gas.