The defence ministry is examining allegations of purposely ignoring unfavourable results of evaluation reports to buy controversial Swedish fighter jets.
A spokeswoman said Defence Minister Ueli Maurer had no knowledge of the confidential reports leaked to a Sunday newspaper.
The allegations are the latest in a series of controversies over the purchase of new jets to replace the F-5 fighters for the air force.
The cabinet last November decided to buy 22 Gripen fighters, worth SFr3.1 billion ($3.4 billion) from Swedish company Saab, rejecting two other rival offers. But parliament is still to decide on the funding for the acquisition amid a challenge by a pacifist group to block it altogether in a nationwide vote.
Tests carried out in 2008 apparently showed that the Gripen fighter was clearly inferior to its rivals, Dassault’s Rafale and Eurofighter.
A report compiled later gave the Gripen slightly better marks but pointed out that it could not fulfil crucial demands of policing Swiss airspace.
The latest allegations have prompted a flurry of comments by parliamentarians and newspaper reports.
Critics called for Maurer to step down if he was found lying or hiding crucial facts. Others see the controversy as part of ongoing efforts to outbid rivals.
swissinfo.ch and agencies