It is common practice for European manufacturers to subsidise the price of handsets, a policy that benefits the consumer through lower prices and stimulates the market in the process.
The majority of the companies publicly stated their intention to lower the subsidies on cell phones with effect from 1 September.
Hugo van Bergen, a spokesman for Dutchtone NV, the Dutch subsidiary of the French mobile phone company Orange, said, "The NMa was looking for evidence that could point to fixing of handset subsidies by the operators. There is no such price-fixing, and that will undoubtedly be the conclusion of the NMa investigation."
The other operators - KPN Mobile NV, Ben Nederland Holding BV and Telfort Mobiel BV - also expressed surprise at the Nma raids and emphasised that they too were innocent of any wrongdoing relating to subsidies. The investigation is expected to last between six months and a year.