Sony has begun a worldwide recall of tens of thousands of laptop computers and blank recordable DVD discs. The company said last week that oxidation on the protective layer of some DVD+RW discs could leave black spots on the surface, rendering the discs unreadable. The discs were manufactured for Sony by magnetic storage giant Ricoh. Most of the affected discs were bundled with Sony's DVD+RW/ DVD-RW computer drives, although the company said some had been sold separately. The problem does not affect the drives themselves. 'They were in very small quantity, but we cannot let you know the quantity. It mostly affects the discs that went out as part of the bundles,' a Sony spokeswoman said. As many as 18,000 discs are being recalled worldwide, according to Kyodo news agency. Sony would not reveal how many had been sold in Hong Kong or Macau. Sony on Thursday also announced that 13,000 Sony Vaio notebooks could have defective power supplies with the potential to cause electric shocks. The fault could cause a minor electric shock if the user was touching a mains-connected laptop that was plugged into a phone when it rang, a spokesman said. The Vaio recall affects 13,000 notebooks sold in Japan, 3,000 in the United States and 2,000 in Europe. None of the affected models has been officially shipped in Hong Kong, but Sony, recognising the large so-called parallel import market here, said Hong Kong customers would also qualify for free repairs. Reports estimate that the recall will cost Sony 500 million yen (about HK$33.1 million). Last year, Sony was forced to recall 40,000 desktop PCs in Japan, the US and Canada. Sony said affected discs could be exchanged at Sony's customer service centres in Causeway Bay, Mongkok or Macau. More information is available on Sony's website at e-cs.sony.com.hk, or call the 24-hour hotline at 2345 2966. The replacement offer runs until October 31.