Saab, the maker of Gripen jets, has said the centre-right government's plan to buy at least 60 jets of the new model will cost around US$ 5 billion.
But Swedish Radio's sources said the price could end up being around ten percent higher.
"The big question is what we need them for, because the threat levels do not demand investments of this size," said Peter Rådberg, the Green Party's representative in the parliamentary committee on defence.
"There needs to be an upgrade if we are to have an operational and relevant jet fighter system in the 2020's and towards 2030," said the lieutenant general Jan Salestrand, adding that though it is needed, the new purchase cannot come at any price.
On Monday, the Swedish Army will announce which other defence projects may need to be pushed back as a result of the investment in new fighter jets.