Six cases of the H1N1 virus have been confirmed among 75 recruits at a Swiss army base who are experiencing flu-like symptoms.
The defence ministry said it should be assumed that most of the recruits involved are suffering from the pandemic flu.
In all, 324 soldiers are currently stationed at the Chur base in eastern Switzerland but a quarantine of all the residents has been ruled out for the moment.
The army and the cantonal doctor will decide on any further measures that may need to be taken, a ministry spokesman said.
Switzerland has recorded more than 1,550 confirmed cases of swine flu, including 30 patients who had to be admitted to hospital, but no deaths so far.
A national vaccination programme will be carried out in two phases beginning in mid-November.
swissinfo.ch and agencies