The raids, on March 10, were part of an ongoing investigation into possible anticompetitive agreements between electronics retailers and manufacturers, a European Commission spokesman said in an email.
"The Commission has concerns that the companies concerned may have violated EU antitrust rules that prohibit anticompetitive agreements or concerted practices," he added.
The raids are a follow-up of inspections conducted in December 2013, when the Commission raided Samsung Electronics, Philips and electronics retailer Media-Saturn, among other companies.
The spokesman would not name the companies raided this month, nor say whether the Commission targeted the same companies as in 2013.
Samsung and Philips did not immediately respond to a request for comment.
Staff at Media-Saturn, one of Europe's largest electronic retailers, would not immediately comment.
The investigation does not concern three other major electronics retailers, Dixons-Carphone, Darty and Euronics, staff reached at those companies said.
The Commission has grounds to suspect the companies raided have restricted online sales of consumer electronics products and small domestic appliances, which might lead to higher prices for consumers or the unavailability of products in some online shops.
Unannounced inspections are a preliminary step in investigations into suspected anticompetitive practices. There is no legal deadline for these investigations to be completed. If a company is found to have participated in an anti-competitive agreement, it can be fined up to 10 percent of its annual turnover.
Loek is Amsterdam Correspondent and covers online privacy, intellectual property, online payment issues as well as EU technology policy and regulation for the IDG News Service. Follow him on Twitter at @loekessers or email tips and comments to loek_essers@idg.com