Merckx could not be reached for comment but the 70-year-old five-time Tour de France winner was quoted by the newspaper, La Derniere Heure, as saying: "I have nothing to say. We'll see what happens."
Asked about the report on Merckx, the public prosecutor's office would only say that a case had been opened. A spokesman declined comment on whether prosecutors wanted Merckx to face a graft trial after summer with 12 others, as the newspaper said.
The newspaper said the cyclist, who won the Tour and the Giro d'Italia five times each between 1968 and 1974, is suspected of giving a local police chief a discount on two Eddie Merckx bikes made by his company and securing a 15,000-euro (11,360 pounds) contract to supply 46 bicycles to the Brussels-Midi police force in 2006.
The police chief and several others were indicted in 2012 but an eventual trial could now involve more people, DH said.
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Dubbed "The Cannibal" for his appetite for winning, Merckx founded his eponymous cycle company in 1980. He stepped down as chief executive in 2008 but remains involved, the firm says.
A national hero, Merckx has a metro station named after him in the borough of Anderlecht, served by the Midi police force.
(Editing by Alastair Macdonald/Jeremy Gaunt)
