The gas deal is likely to be signed during a visit by Russian Foreign Minister Sergey Lavrov to Belgrade early in June.
As the war in Ukraine rages, Serbia's president announced that he has secured an "extremely favourable" natural gas deal with Russia during a telephone conversation on Sunday with his Russian counterpart Vladimir Putin.
Serbian President Aleksandar Vučić has refused to explicitly condemn Russia's invasion of Ukraine, and his country has not joined Western sanctions against Moscow -- one of a handful in Europe, including Belarus and neighbouring Bosnia.
The country's national air carrier Air Serbia is also among a few on the continent that still operates flights to Russia.
Vučić claims he wants to take Serbia into the European Union but has spent recent years cementing ties with Russia, a long-time ally.
The gas deal is likely to be signed during a visit by Russian Foreign Minister Sergey Lavrov to Belgrade early in June — a rare visit by a ranking Kremlin official to a European country since the Russian invasion of Ukraine began on 24 February.
Vučić said he told Putin that he wished "peace would be established as soon as possible".
Serbia is almost entirely dependent on Russian gas, and its main energy companies are under Russian majority ownership.
"What I can tell you is that we have agreed on the main elements that are very favourable for Serbia," Vučić told reporters.
"We agreed to sign a three-year contract, which is the first element of the contract that suits the Serbian side very well."
It is not clear how Serbia would receive the Russian gas if the EU decides to shut off the Russian supply that travels over its member countries. Russia has already cut off gas exports to EU members Finland, Poland and Bulgaria.
The EU as a whole has been hurriedly reducing its reliance on Russian energy since the invasion and is set to discuss ways to further do so and to hear from Ukrainian President Volodymyr Zelenskyy during a leaders' summit that starts Monday.
Despite reports of the atrocities in Ukraine due to the invasion, Vučić and other Serbian leaders have been complaining of Western pressure to join sanctions against Russia.
Serbian officials say the Balkan country must resist such pressure, even if it means abandoning the goal of joining the EU.
During Vučić's 10-year rule, Serbia has kept close ties with Putin and Moscow, as well as China.
In recent weeks, the country has been plagued by numerous bomb threats on its flights to Russia, as well as public institutions, schools, the Belgrade airport and the zoo.
The origin of the threats is still unclear, but some in Vučić's government have indicated they believe they are connected to the country's hesitance to align with the EU against Russia.
"The agreement reached by President Vučić with President Putin is proof of how much Serbia's decision not to participate in anti-Russian hysteria is respected," Interior Minister Aleksandar Vulin said.
"The free leader, free people, make decisions that are good for Serbia and do not accept orders" from the West, said Vulin, who is known for his pro-Russian stance.