BEIJING -(Dow Jones)- A China joint venture under Microsoft Corp. (MSFT) will announce a new partnership with Sina Corp. (SINA) at a news briefing on Thursday, a spokeswoman for the joint venture, Viola Wang, said Tuesday. Liu Qi, vice general manager of Sina's business management center, confirmed the company will announce a partnership with Shanghai MSN Network Communications Technology Co. The companies didn't provide further details of the coming announcement. Shanghai MSN Network Communications Technology, also called MSN China, is a joint venture between Microsoft and Shanghai Alliance Investment Ltd. It operates Microsoft's Internet services in China. -By Owen Fletcher, Dow Jones Newswires; 8610 8400 7702; owen.fletcher@dowjones.com (Loretta Chao and Sue Feng contributed to this article.)