The European Commission has raided the offices of several glassmakers, including Pilkington, the world's largest manufacturer of car windshields, as part of a probe into a suspected price-fixing cartel.

Commission spokesman Jonathan Todd said the EC had "carried out unannounced inspections at the premises of several manufacturers of flat glass and car glass" on Tuesday and Wednesday.

"The European Commission has reason to believe the companies may have co-ordinated price increases and agreed on the introduction of an energy surcharge in the area of flat glass," he said.

He added that the EC has information that glass producers may have allocated customers and agreed on supply quotas and prices.

The raids could trigger a prolonged investigation into the manufacture of flat glass, which is used in the building industry. There is no set length for such investigations, but they can typically last for around 18 months.

Companies that are found to have violated EU competition rules by operating a cartel are liable to fines of up to 10 per cent of their annual worldwide turnover but usually escape with lower penalties.

The largest fine imposed on a single company was around £350 million against the Microsoft last year. That figure amounted to less than 2 per cent of the software giant's sales.

Pilkington, which is based in St Helen's, confirmed that EC officials had visited a number of its offices in Europe to inspect documents in connection with alleged infringements of Article 81 of the Treaty of Rome. It said it was cooperating with the inspection.

The Paris offices and a German factory of Saint-Gobain, which made the glass for the pyramids at the Louvre, were also raided.

A spokeswoman for Glaverbel, a Belgian subsidiary of Japan's largest glass maker, Asahi Glass, confirmed that it was also part of the cartel probe.

The EC investigation also encompassed offices in Italy and Sweden.

Shares in Pilkington fell as much 5.5p, or 4.5 per cent, to 115.5p on the news before recovering to trade at 118.25p in mid-morning trade.

Shares in Saint-Gobain fell 70 cents to 45.75 euros in Paris.

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