Explosives have reportedly been found near a gas pipeline in Hungary. The Hungarian prime minister, Viktor Orban, has called an emergency meeting of the National Defence Council.

The discovery of two rucksacks full of explosives and detonators was made in the village of Tresnjevac, near the border with Serbia, 12 miles from a TurkStream pipeline that carries Russian oil into Hungary.

Serbian president and ally of Orban, Alexander Vucic, said in a post on Instagram: “Our units found an explosive of devastating power. I told PM Orban that we would keep him updated on the investigation.”

The Hungarian opposition leader, however, has accused Orban of “panic-mongering” orchestrated by “Russian advisers” after his party fell behind in opinion polls ahead of next week’s elections. The discovery came days after security experts warned there could be a “false flag” operation by Hungary. They said it would be blamed on Ukraine to raise sympathy for Orban’s party or give him an excuse to declare an emergency and cancel the election.

A false flag operation is a harmful, often militant, event or action designed to appear as if perpetrated by someone other than the person or group responsible.

Balint Pasztor, president of the Vojvodina Hungarian Association, and another key Orban ally, said on Facebook: “If the investigation proves that we were not the primary target after all, but rather Hungary’s supply lines, then this makes it even clearer: the terrorist attack was planned with the aim of bringing down Viktor Orban.”

Orban, an ally of Putin, has resisted calls to stop Russian gas imports since the invasion of Ukraine. Hungary receives between five and eight billion cubic metres of Russian gas a year through the pipeline.

Orban claims that a European alliance is conspiring to stop Hungary from getting Russian fuel, to impose a “puppet” prime minister of their choice in the upcoming election.

The prime minister also claims that Ukraine is blocking oil from Hungary, with no Russian oil coming through the Druzhba pipeline since January.

The pipeline crosses through Ukraine, which says that it was damaged in a Russian attack and will hopefully be functional again in mid-April.