Bulgaria said Saturday it had unblocked 1,800 tonnes of jet fuel from its state reserves to prevent a shortage at its airports, after its sole refinery halted production over a licencing row. "We unblocked overnight enough jet fuel from the state reserves to last all airports the whole of next week," Economy and Energy Minister Traicho Traikov told national radio. Bulgaria's major airports -- in the capital Sofia and the Black Sea cities of Varna and Burgas -- raised alarm that their stocks of jet fuel would run out next week, in the midst of the busiest summer holiday season, after the country's sole refinery halted production on Friday. The Russia-owned Lukoil Neftochim refinery in Burgas was forced to shut after the customs agency stripped it of two key licences, effectively blocking its operations. The move was prompted by Neftochim's failure to install additional fuel meters and other equipment to link its production and storage warehouses to the Bulgarian revenue agency, enabling it to control the amounts of crude and fuel entering and exiting the refinery. The refinery, which has a capacity of 142,000 barrels per day, is Bulgaria's sole supplier of jet fuel. It also has a 70-percent share in the country's wholesale fuel market and a 25-percent share in the retail market through its chain of 200 petrol stations. Finance Minister Simeon Djankov defended the customs agency's move on Friday, saying that it "only applied the law." "Out of 85 company warehouses that had to be linked to the revenue agency, 76 did so by the end-June deadline and the rest, including those of Lukoil Neftochim, were shut." Bulgaria has state reserves of jet fuel to last up to 68 days and enough car fuel for 80 days, Djankov added. Fuel can also be easily imported from refineries in neighbouring countries, he said.