The Netherlands should go ahead with participating in the F-35 fighter test programme because pulling out at this stage would incur substantial costs, a government think-tank said.
But the Court of Audit report stopped short of recommending whether it thought the Netherlands should stay in the whole F-35 project - which is controversial because of cost overruns and delays - or opt for a different type of plane.
Lockheed Martin Corp is developing three models of the new fighter for the United States and eight other countries - Britain, Canada, Australia, Italy, Turkey, Denmark and Norway as well as the Netherlands.
Pentagon data in April forecast the projected total cost to develop, buy and operate the F-35 at $1.51 trillion over the next 50-plus years, up from about $1.38 trillion a year ago, including inflation.
Prime Minister Mark Rutte's Liberal Party, which won last month's parliamentary election, is in coalition talks with the Labour Party.
A decision on the plane is expected once a new government is in place, although the two parties have different views. Labour called in July for an end to Dutch participation in the project, while Rutte's party has always been in favour.
The Netherlands already owns one F-35 test plane but political parties have questioned whether to go ahead with the full programme because of cost overruns.
"We think pulling out of the test phase is not a logical option because on balance this would only bring disadvantages for the state in terms of functions, time and money," the Court of Audit said on Wednesday in its report on the F-35.
It added that if the Netherlands pulled out of the project and later decided to buy the plane or an alternative, it would face risks in terms of costs and availability.
The Court of Audit, whose recommendations are not binding, is an independent think tank which advises the cabinet and checks its spending and policy decisions.
Outgoing Defence Minister Hans Hillen welcomed most of the report's conclusions and said in a statement 56 F-35 planes were sufficient to meet the Netherlands' air force operations.
The Netherlands has 68 F-16 planes and Hillen said in April he would buy fewer than the originally planned 85 F-35s.