BRUSSELS (Reuters) - EU antitrust regulators told 13 optical disk drive producers on Tuesday that they may have breached EU rules by rigging bids over a five-year period as part of a worldwide cartel that may lead to fines for the companies involved.

The European Commission said it had sent statements of objections or charge sheets to the companies, which it did not name in line with its usual policy.

"The Commission has concerns that those suppliers may have coordinated their behavior in bidding events organized by two major original equipment manufacturers for optical disk drives used in personal computers (desktops and notebooks) and in servers," the EU watchdog said in a statement.

Optical disk drives read or write data on CDs and DVDs.

(Reporting by Foo Yun Chee; editing by Philip Blenkinsop)