Philips and Samsung Electronics said today they were among the companies visited by European Commission officers this week on suspicion of breaking competition rules.
The two companies said that they were co-operating with the inspectors.
The European Commission said today its officers had raided several companies involved in making and selling consumer electronics and small domestic appliances.
This follows concerns that the firms had worked together to limit the sale of some goods online to drive up their prices.
It did not give details of the name or location of the companies inspected by its officers on December 3.
The investigation comes as traditional electronics retailers wage a fierce battle with online rivals such as Amazon.
The EU competition regulator can fine companies up to 10% of their global revenue for breaking EU rules.
The companies said they were co-operating with the EU authorities, but declined any further comment.