Sony, the Japanese electronics group, is to launch two new low-cost electronic book readers on Wednesday aimed at broadening the market for digital reading devices and challenging Amazon’s Kindle readers in the US market.

Sony’s Reader Pocket Edition comes with a 5-inch screen, is designed to fit easily in a pocket or purse, can store about 350 books and will cost $199 while the Reader Touch Edition has a larger touch-sensitive screen and will cost about $299.