The United States firm, Biogen, says it has filed a complaint with the Geneva prosecutor against Serono after the Swiss drugs company broke a court order banning publication of data comparing the firms' multiple sclerosis drugs.
In a briefing in London on Monday, Biogen said Serono broke the injunction by repeating claims that patients treated with its drug, Rebif, were less likely to suffer relapses than those on Avonex.
Biogen says its complaint accuses Serono of contempt of court. If found guilty, Serono's management could face imprisonment, although a fine is more likely. The maximum fine is SFr5,000 ($2,780).
Serono accuses Biogen of using the injunction to suppress the publication of a study into the rival drugs. Biogen counters that the survey's methodology was flawed.
swissinfo with agencies