SHANGHAI, April 15 (Reuters) - China stocks had a good start to the week with major indexes up as investors interpreted the guidelines on the country's capital market as a positive signal for the stock market. Hong Kong shares declined.

China's securities regulator issued draft rules on Friday to strengthen the supervision of company listings, delistings and computer-driven programme trading, in a move to improve the stock market and protect investors' interests.

UBS strategist Lei Meng believes that the updated policies would fundamentally guide the long-term healthy development of the capital market, improve the quality of listed companies and boost market confidence.

** At the midday break, the Shanghai Composite index .SSEC was up 1.21% at 3,055.99 points.

** China's blue-chip CSI300 index .CSI300 was up 1.9%, with its financial sector sub-index .CSI300FS 1.68% higher, the consumer staples sector .CSI000912 rose 2.36%, the real estate index .CSI000952 advanced 1.01% and the healthcare sub-index .CSI300HC jumped 1.43%.

** Chinese H-shares listed in Hong Kong .HSCE fell 0.41% to 5,855.59, while the Hang Seng Index .HSI was down 0.73% at 16,599.34.

** The smaller Shenzhen index .SZSC was up 0.26%, the start-up board ChiNext Composite index .CNT was 2.1% higher and Shanghai's tech-focused STAR50 index .STAR50 was up 1.91%​.

** Around the region, MSCI's Asia ex-Japan stock index .MIAPJ0000PUS was 0.85% weaker, while Japan's Nikkei index .N225 was down 1.04%.

** The yuan CNY=CFXS was quoted at 7.2386 per U.S. dollar, 0.02% weaker than the previous close of 7.2372.

** The largest percentage gainers in the main Shanghai Composite index were Shaanxi Construction Machinery Co Ltd 600984.SS, up 10.13%, followed by Wolong Resources Group Co Ltd 600173.SS, gaining 10.07% and Shanghai Shyndec Pharmaceutical Co Ltd 600420.SS, up by 10.05%.

** The three biggest H-shares percentage decliners were SenseTime Group Inc 0020.HK, falling 4.55%, Li Ning Co Ltd 2331.HK, lost 4% and Xpeng Inc 9868.HK was down 3.74%.

(Reporting by Shanghai Newsroom; Editing by Sonia Cheema)

((li.gu@tr.com))