(Corrects to show corn prices fell by a quarter since June not 20 percent in 2nd paragraph)
BEIJING, Sept 30 (Reuters) - China has given approval to at least two companies to export corn, two sources with knowledge of the matter said, in a radical move by the world's No. 2 producer to cut its ballooning surplus that could add more supply to a saturated global market.
The move threatens to push prices down sharply in a market that has already fallen a quarter since June.
In what could be the first bulk exports in a decade, the government has issued permits to two state-owned companies, top grains trader Cofco and major processor and trader Beidahuang, allowing them to sell grain abroad, said China-based sources who asked to remain anonymous because they were not authorised to speak to the media. (Reporting by Domininque Patton; Editing by Christian Schmollinger)