The Federal Health Office has been hit with legal action over its decision to ban Hong Kong-based firms from attending an international watch and jewellery fair in April.
The fair's organisers and the Hong Kong Trade Development Council (TDC), have lodged separate appeals against the ban, claiming it was illegal and unreasonable.
Both parties say they are also considering claims for damages.
Bernhard Keller, spokesman for the BASELWORLD fair, told swissinfo that the ban was excessive and not based on a realistic appraisal of the situation.
Health officials imposed the ban on exhibitors and staff from Hong Kong, China, Singapore and Vietnam just two days before the fair opened.
Thomas Zeltner, director of the Federal Health Office, said the restrictions were designed to prevent the spread of Severe Acute Respiratory Syndrome (Sars).
The ban affected more than 300 exhibitors and around 2,500 staff from Hong Kong - the second biggest delegation at the fair behind the Swiss.
At the time, the TDC placed the cost at having to withdraw from the fair at around HK$50 million (SFr8.43 million) in airfares, hotels and marketing costs. The total loss of trade is estimated to be far higher.
Keller said the ban was unlawful and unreasonable, arguing that the ban had prevented people from manning their stands but not from attending the fair as visitors.
"The measures imposed made no contribution whatsoever to the protection of the [Swiss] population," he said.
Elke Brockmann, spokeswoman for the TDC, told swissinfo that the measure was "discriminatory and unjustified" and had led to heavy financial losses for Hong Kong firms.
"The decree was enforced in such a way that the firms were unable to conduct business at the stands [during the fairs]," she added.
Responding to the news of the appeals, the Federal Health Office defended its decision to restrict access to BASELWORLD, saying it was justified in taking such action at a critical phase of the Sars epidemic.
"To have underestimated the situation could have lead to a disaster in Switzerland," said vice-director Dieter Hartmann.
Geneva-based lawyer Charles Poncet said the appeals were unlikely to succeed, as there was sound justification for the Federal Health Office's decision.
"Having to chose between harming people or causing [others] difficulty because they are prevented from entering Switzerland [due to the] risk of Sars, it's quite obvious the balance falls on the side of caution," said Poncet.
"I would be very surprised if this was overturned on appeal. To put it bluntly, the appeals don't stand a chance in hell," he added.
swissinfo, Faryal Mirza
BASELWORLD fair organisers and the TDC have lodged separate appeals against last month's watch and jewellery fair ban.
They said the Federal Health Office's decision was illegal and unreasonable.
They are also considering claims for damages.
Swiss health officials said the ban was aimed at halting the spread of Sars.
The TDC estimated it cost SFr8.43 million to withdraw from the fair.