The backpacks, containing “two large packages of explosives with detonators”, were found in Kanjiza in northern Serbia, “a few hundred metres from the gas pipeline”, Vucic said.

The Balkan Stream pipeline is an extension of the TurkStream pipeline that carries Russian gas to Serbia and Hungary.

Vucic said he had informed Hungary’s Prime Minister Viktor Orban “of the initial results of the investigation by our military and police authorities into the threat to the critical gas infrastructure”.

No details were given on possible motives, but Vucic said there were “certain traces” he could not discuss straight away. “Our intelligence services did a good job,” he declared.

Vucic said the explosives could have “endangered many lives” and caused significant damage to the pipeline.

Serbia, an EU candidate, is heavily dependent on Russian gas, importing about six million cubic metres per day at about half the market price.