** Hong Kong-listed shares of China Petroleum & Chemical Corp (Sinopec) 0386.HK slip 1.8% to HK$3.87, their biggest intraday pct fall since April 7

** Stock touches the lowest point since April 22, and on course to snap two straight sessions of gains

** Stock is third-biggest pct decliner on the Hang Seng China Enterprises Index .HSCE, which adds 0.4%

** Shanghai-listed stock 600028.SS slips 1.1% to 5.65 yuan, its biggest one-day pct fall since April 21

** The world's largest refining group by capacity said its first-quarter profit fell by 27.6% year-on-year, weighed down by lower oil prices and as its refining operations grappled with declining fuel sales and thin margins

** The Hang Seng Composite Index, which tracks energy stocks .HSCIE, slips 0.6% and Hang Seng Mainland Oil & Gas Index .HSMOGI eases 0.7%

** YTD, Hong Kong stock down 12.8%, Shanghai shares down 14.5%

(Reporting by Donny Kwok)

((donny.kwok@thomsonreuters.com))