BELGRADE (Reuters) - Gas flows from Azerbaijan to Serbia have been halted and it is unclear when they will resume, news agency Tanjug quoted Serbian President Aleksandar Vucic as saying.

"I got information from our Azerbaijan brothers and friends that because of force majeure, and problems they have, we as of today cannot count on 1.7 million cubic metres of gas that was coming every day," Vucic told reporters.

Vucic said it was not clear when the gas flows would resume.

"This means that as of today we will start spending gas reserves," Vucic said, adding that he hoped in a month or two gas flows would resume.

In 2023, Serbia, which uses more than 3 billion cubic metres of gas a year, signed a deal with Azerbaijan to purchase 400 million cubic metres of natural gas per year from 2024.

The rest of the gas comes from Russia.

Serbia, which aims to join the European Union, is under pressure to reduce its dependence on Russia for gas and oil.

Following new U.S. sanctions on Russia's oil sector, Russia's Gazprom Neft will be given 45 days to exit ownership of Serbian oil company NIS, which is among the biggest contributors to Serbia's budget.

NIS is majority owned by Gazprom Neft, which holds a 50% stake, and Russia's Gazprom, which holds 6.15% of shares. The Serbian government holds 29.87%, with small shareholders accounting for the remainder.

Bulgaria also said earlier this week that Azerbaijan had suspended contracted gas supply from Jan. 7 until Jan. 11 because of unspecified technical reasons.

The interruption came as BP's Azerbaijan unit said on Friday it had suspended the work of the Shah Deniz Alfa (SDA) platform after detecting a technical issue at the subsea gas condensate export line.

BP did not immediately respond to a request for comment on Saturday about gas exports from Azerbaijan to Serbia.

(Reporting by Ivana Sekularac. Additional reporting by Vladimir Soldatkin. Editing by Mark Potter)