SINGAPORE, May 5 (Reuters) - Hong Kong shares edged lower on Tuesday as rising tensions in the Middle East dampened risk sentiment, while mainland Chinese markets remained closed for a holiday.

** Hong Kong's benchmark Hang Seng Index .HSI was down about 0.9% at 25,871 in mid-morning trading. Brent crude futures LCOc1 hovered around $113 a barrel, reflecting ongoing geopolitical concerns.

** The U.S. and Iran launched fresh attacks in the Gulf as they wrestled for control over the Strait of Hormuz with duelling maritime blockades, not long after U.S. President Donald Trump established a new effort to get stranded tankers and other ships through the vital energy-trade chokepoint.

** Despite the broader sentiment, investor appetite showed resilience. Shares of Star Sports Medicine 1609.HK surged 146.3% to HK$242.6 on their trading debut, underscoring strength in the IPO market.

** The China-based medical device company, which specialises in clinical sports medicine, raised HK$827.4 million ($105.62 million), with the Hong Kong public offering 7,823.13 times subscribed.

** "The IPO market is still hot," said Kenny Ng, a securities strategist at China Everbright Securities International.

** Macau gaming stocks extended modest losses. Although April revenue increased year-on-year, growth slowed compared with levels seen in March, weighing slightly on the sector.

** Sector-wise, energy shares .HSCIE dipped 0.4%, while information technology .HSCIIT stocks declined 1%.

** Among blue chips, Contemporary Amperex Technology 3750.HK led gains with a 2.53% rise, whereas Techtronic Industries 0669.HK was the biggest laggard, dropping 4.18%.

** Regional trading volumes were subdued due to holidays in Japan and South Korea. MSCI's Asia ex-Japan index slipped 0.45%, reflecting a cautious tone across markets. MKTS/GLOB

** Meanwhile, Chinese ADRs .HXC edged down 0.09% overnight.

** The offshore yuan CNH= held steady at 6.83 per dollar and remains the best-performing Asian currency against the greenback since the Middle East conflict erupted on February 28.

($1 = 7.8349 Hong Kong dollars)