Hungary on May 23 stuck to its demands for energy investment before it agrees to a Russian oil embargo, clashing with EU states pushing for swift approval of more EU sanctions against Russia for invading Ukraine.

The EU commission early this month proposed the new package of sanctions against the Kremlin but the measures have not yet been adopted, with Hungary being among the most vocal critics of the plan.

"Solutions first, sanctions afterwards," Hungary's Justice Minister Judit Varga told journalists ahead of ministerial talks in Brussels on May 23.

That clashed with calls from several governments for a deal before a summit of the EU's leaders on May 30.

Hungary, which is heavily dependent on Russian oil, has said it would need about 750 million euros ($800.8 million) in short-term investments to upgrade refineries and to expand a pipeline bringing oil from Croatia.

It has also indicated that in the longer run the conversion of its economy away from Russian oil could cost as much as 18 billion euros.

The commission last week offered up to 2 billion euros in support to land-locked central and eastern European countries that lack access to non-Russian supply – effectively Hungary, the Czech Republic and Slovakia.

These states have also been offered a longer transition period to wean themselves off Russian oil.

To address longer-term concerns, the commission has published a 210 billion euro plan meant to end Europe's reliance on Russian fossil fuels by 2027 but has not indicated how the new investments would be shared among EU states.

One of the key stumbling blocks remains the amount the EU is ready to pay to Hungary to adapt two refineries that at the moment can only process Russian crude, an official told Reuters, confirming one of the key issues causing the deadlock.

At a meeting of EU diplomats last week, several envoys, including those from France, Lithuania, Belgium and Ireland, urged a compromise before the EU summit next week to avoid a political escalation of the controversy, diplomats said.