Budapest opposes measures “that might have a negative impact on EU gas market” — a stance that could kill the EU’s effort to squeeze Moscow’s gas revenue.

The EU’s unprecedented effort to penalize Russia’s lucrative gas sector is already crashing into a familiar sanctions foe: Hungary.

The country expressed significant reservations about the new proposal during initial conversations among ambassadors last week, according to several people in the room — refusing to oppose the measure outright but making its wariness evident. Hungary’s top envoy said his country would block any penalties that raise energy costs in Europe.

“We are going to analyze the package but do not support anything that might have a negative impact on [the] EU gas market,” the Hungarian official said during a meeting of diplomats on Wednesday, according to two diplomats with knowledge of the discussions.