Tmall, the business-to-consumer shopping site under China's largest e-commerce firm, the Alibaba Group, yesterday said it will offer 1 billion yuan (US$159 million) in discounts to consumers as well as subsidy for external vendors in the second half to boost sales.

Tmall's move was seen as a response to a similar sales campaign by rival 360buy.com.

Tmall said yesterday it would offer cash vouchers for online buyers for every order worth 800 yuan, and the higher value of the order, the more cash vouchers consumers will receive.

The discount will cover all product categories, including clothing and apparel, home furniture and baby products.

Tmall earlier estimated that sales this year may double from 2011 to reach 200 billion yuan with digital device and home appliances making up 50 billion yuan.

Another major online rival, Tencent, said in May that it will inject US$1 billion into its e-commerce unit to upgrade its service and boost sales.