The leaders of Serbia and Hungary announced on Sunday that explosives were found near a pipeline in Serbia that transports Russian gas to Hungary.
"Our units found an explosive of devastating power," Serbian President Aleksandar Vucic said in a post on Instagram.
He said "two large packages of explosives with detonators" were found in Kanjiza, in the north of Serbia, "a few hundred metres from" the Balkan Stream gas pipeline.
Hungarian Prime Minister Viktor Orban called a meeting of his country's Defense Council to discuss the situation.
"According to information that we have [...] there was an act of sabotage prepared," Orban said after the meeting.
The two leaders did not immediately provide further details of the findings or provide photos.
Serbia, Hungary say explosives found near Russian pipeline
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Ukraine rejects any connection
Balkan Stream is a pipeline that runs through Bulgaria and Serbia, connecting Hungary with Russian gas piped under the Black Sea to Turkey.
Orban said "Ukraine has been trying for years to cut off Europe from Russian energy," but he stopped short of directly blaming Ukraine or any other actor.
Ukraine denied any connection to the alleged sabotage.
"We categorically reject attempts to falsely link Ukraine to the incident with explosives found near the Turkstream pipeline in Serbia," Ukraine's Foreign Ministry spokesperson Heorhii Tykhyi said.
"Ukraine has nothing to do with this. Most probably, a Russian false-flag operation as part of Moscow's heavy interference in Hungarian elections."
Serbia and Hungary are both dependent on importated Russian gas.
In recent weeks, Orban accused Ukraine of intentionally delaying repairs to a separate damaged pipeline through Ukraine, which has choked the flow of Russian oil to Hungary and Slovakia.
EU bans Russian gas, bypassing holdouts Slovakia, Hungary
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Hungarian opposition questions timing
The announcement also comes a week before hotly contested elections in Hungary that could see the nationalist Orban lose power after 16 years.
The lead opposition candidate, Peter Magyar, responded to the news by accusing Orban of attempting to sow panic ahead of the vote.
"Several people have publicly indicated that something will 'accidentally' happen at the gas pipeline in Serbia at Easter, a week before the Hungarian elections," Magyar said in a video posted to Facebook. "And so it happened."
