European anti-trust regulators on Monday launched in-depth probes into proposed US takeovers of South Korean and Japanese businesses manufacturing computer hard disk drives (HDD). The planned acquisitions of the hard disk drive operations of South Korean electronics giant Samsung by Seagate Technology, and the storage business of Japan's Hitachi by Western Digital Corporation in a sector with just five manufacturers worldwide have raised concerns in Brussels, the European Commission said. "Hard drives are the backbone of the digital economy," said EU competition commissioner Joaquin Almunia in announcing the investigation. "The sector has already experienced significant consolidation and the proposed acquisitions will further reduce competition." Used in everything from computers to digital video recorders, Toshiba is the fifth major player. Brussels officials have until October 10 to decide what action if any they will take.