The Competition and Markets Authority (CMA), Britain's competition watchdog, has accused Merck of operating an unfair discount scheme designed to restrict competition from Remicade biosimilars.
The CMA said it had provisionally found Merck's European unit had been abusing its dominant position, which opens up the drugmaker to financial penalties.
Merck allegedly offered a discount to customers who continued to buy Remicade in the same quantities but only if they did not begin buying biosimilars.
Merck said it does not believe it has broken any rules and is cooperating fully with the CMA. Merck argues that its pricing was to keep Remicade competitively priced without hindering competition.
The CMA can fine companies up to 10 percent of their global turnover if found to have breached competition law.
Read the Reuters report