The Balkan country, which has been a NATO member since 2004, has been looking for some years to replace its ageing and dwindling fleet of Soviet-built MiG-29 planes.

But since Moscow's forces invaded Ukraine in February, it has been unable to buy spare parts or engines to service those planes from Russia. It has instead been negotiating to buy two MiG-29 engines from Poland and send six more there for repairs.

The country paid $1.67 billion for the first eight F-16 jets from Lockheed Martin, hoping to receive them in 2023.

But their delivery has been delayed and Interim Defence Minister Dimitar Stoyanov has said they might now not arrive before 2025.

Parliament on Friday green-lit the new deal with 162 votes in favour, 49 against and 11 abstentions.

Under it, the country is by 2031 to pay an additional $1.32 billion for four single-seater and four two-seater F-16 Block 70 fighter jets plus weapons, due to be delivered by 2027.

In order guard its airspace, Bulgaria is looking for ways to rent or buy used fighter jets from Sweden or France.

For now, aircraft and crew from Spain, the Netherlands and the United States have taken turns helping with air policing, with six Eurofighter jets and 130 crew expected to arrive on a new mission in Bulgaria in mid-November.

Parliament tasked the country's interim government on Thursday to study the possibility of sending any defence equipment it might spare to Ukraine -- a U-turn for the country, where a large part of the population remains pro-Russian.

vs-ds/jza/ah

LOCKHEED MARTIN