* EU says raided firms in special glass sector
* Glass used in optical and electronics applications
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BRUSSELS, July 3 (Reuters) - The European Commission said on Friday it had raided the premises of a number of companies in the special glass sector on suspicion of cartel activities but did not identify them.
"The Commission has reason to believe that there may have been a violation in this sector of rules on restrictive business practices," the 27-country European Union's executive arm said in a statement.
The Commission said the raids took place on March 4 and there was no strict deadline to complete its probe.
Special glass products are used for optical and electronics applications in the commercial and industrial sectors, it said.
It said such raids are preliminary steps in investigations into suspected cartels and that it was not prejudging the outcome of the investigation.
The Commission, the European Union's antitrust watchdog, can fine companies up to 10 percent of annual turnover if they are found guilty of antitrust violations. Last year, it slapped an 896 million euro fine -- the second highest penalty on an individual company -- on glass maker Saint-Gobain for price fixing. (Reporting by Bate Felix, Editing by Timothy Heritage/Dale Hudson)