Swiss police say a container of swine flu virus samples packed in dry ice burst late Monday as it was being shipped on a Swiss train from Zurich to Geneva.
Authorities attribute the accident to bad packaging and say it posed no threat to humans.
Police said the container held vials of a strain of swine flu virus different from the H1N1 variety responsible for a worldwide alert and for the deaths of about 150 people in Mexico.
The material was being transferred to Geneva as part of Swiss efforts to develop an effective test for detecting swine flu in humans.
Reuters news agency says police stopped the train ahead of its arrival in Lausanne. Authorities report one person injured in the incident.
Some information for this report was provided by AP and Reuters.