BRUSSELS — European Union antitrust authorities said on Thursday that they had investigated major telecommunications companies, including Deutsche Telekom of Germany, on suspicion that the companies were using their dominant market positions to limit Internet providers’ access to their networks.

The European Commission, the executive arm that oversees antitrust policy across the 28-member bloc, did not identify the companies or say how many had been inspected in the operation, which took place Wednesday.

But Deutsche Telekom confirmed on its Web site that a raid had occurred, adding that e-mails and other data had been seized. Reuters reported that the authorities had also raided the offices of Orange of France and Telefónica of Spain.

Big telecommunications companies provide the networks that link smaller sites, like movie-streaming services, to the Web, effectively acting as a gateway. In a statement, the commission said it was concerned that the companies may have violated antitrust rules “that prohibit the abuse of a dominant market position.” Those companies provide services “crucial for the functioning of the Internet” so consumers can gain access to “Internet content with the necessary quality,” it said.