Bulgaria will ask for proposals from Portugal on providing new U.S. F-16s and from Italy on new Eurofighter Typhoons, to ensure fair competition with Sweden’s Gripen, as the country seeks to buy eight fighter jets.

Bulgaria is looking to replace its ageing Soviet-designed MiG-29s, but plans to buy Gripen warplanes were put on hold last month after lawmakers questioned whether all bidders for the contract had been treated equally.

In June, Bulgaria, a member of NATO and the European Union, said it would start talks to buy the Gripens from Swedish manufacturer Saab, in a deal estimated at 1.5 billion levs ($901.33 million). The country also received offers for second-hand U.S. F-16s and for second-hand Eurofighter Typhoons.

However, a parliamentary committee set up to investigate the bid process, part of which was handled by a previous interim government, requested a defence ministry review after uncovering what it called “disturbing facts”. The committee released no details of those facts.

Bulgarian Prime Minister Boyko Borissov also voiced doubt that Gripen was the best choice for the new fighter jet for the country’s air force.

The three bidders will be given the opportunity to present offers for a new aircraft, too,

Defence Minister Krasimir Karakachanov said on Wednesday.

I believe that if Bulgaria buys airplanes, they have to be new,

said Karakachanov, who is also a deputy prime minister.

We have planes that have a further 15 years (lifespan), we need airplanes with a 30 to 40 years perspective.

The question of which warplanes Bulgaria should buy has been vexing successive governments for more than a decade. Bulgaria has said that between 2018 and 2022 it wants to upgrade to bring its fighter jets closer to compliance with NATO standards.