Drugmaker Bayer said on Saturday it had challenged an Indian patents office order that allowed domestic rival Natco Pharma to sell a cheap generic version of the German firm's liver and kidney cancer drug Nexavar in India.
In March, the patents office stripped Bayer of its exclusive rights to sell Nexavar, saying most Indians could not afford it.
It told Natco Pharma to sell the generic drug significantly more cheaply and pay Bayer a 6 percent royalty on sales.
Bayer said it had appealed against the ruling. "We will rigorously continue to defend our intellectual property rights, which are a prerequisite for bringing innovative medicines to patients," a company spokesman said.
India's decision on Nexavar was seen as a precedent that could extend to other treatments, including modern HIV/AIDS drugs, in a major blow to global pharmaceutical firms.
Separately, Bayer is suing another Indian drugmaker, Cipla, (CIPL.NS) for patent infringement over Nexavar. Cipla has been selling generic Nexavar in India and it has slashed the price of the drug by 75 percent to 6,840 Indian rupees a month.
(Reporting by Kaustubh Kulkarni in Mumbai; Editing by Alistair Lyon)