BEIJING — China's Lenovo Group Ltd will lay off 10 percent of white-collar staff after sales of Motorola handsets fell by a third, raising doubts over the personal computer giant's bet that a money-losing brand it bought for nearly $3 billion will help it become a global smartphone leader. Shares in the world's biggest maker of PCs slid nearly 9 percent on Thursday after it said its quarterly net profit was halved as its mobile division lost nearly $300 million. Lenovo, which uses the US dollar in operations rather than the recently devalued Chinese yuan, said it plans to cut about 3,200 non-manufacturing jobs with a one-time cost of $600 million. Beijing-based Lenovo said the restructuring would yield savings of about $1.35 billion on an annual basis. But the difficulty in selling handsets, combined with a continuously shrinking global market for PCs, meant the firm was facing its “toughest market environment in recent years”, Chief Executive Yang Yuanqing warned. “I still believe mobile is a new business we must win,” Yang told Reuters in an interview, saying Lenovo's ambition to rival Apple Inc and Samsung Electronics Co in smartphones remains undimmed. — Reuters