Serbia's defense ministry says it has taken delivery of four Russian-made MiG-29 fighter jets from Belarus, part of an arms purchase that could heighten tensions in the Balkans and increase Moscow's influence in the region.

Serbian Defense Minister Aleksandar Vulin attended the ceremony at an air force base in Belarus on Monday.

Serbia has recently received six MiG-29 jets from Russia, which has also promised the delivery of 60 armored vehicles. Serbia, a Russian ally, was at war with neighbors Croatia, Bosnia and Kosovo in the 1990s during the bloody breakup of the former Yugoslavia.

Vulin said in a statement that with Monday's delivery of the four secondhand jets that need refurbishing, Serbia will have 14 operational MiG-29s.

He says "our air force has never been stronger in decades."