** S&P 500 energy index .SPNY up 1.2%, tracking higher crude prices O/R

** Brent crude futures LCOc1 up 1.7% at $110.48 a barrel; U.S. West Texas Intermediate crude CLc1 gains 3.4% to $99.40 a barrel

** Crude prices rise as the three-week-old Iran war shows no signs of abating with the U.S. preparing to send thousands of additional troops to the Middle East in coming weeks

** Energy major Chevron CVX.N gains 1.3%

** APA Corp APA.O, ONEOK OKE.N , Exxon Mobil XOM.N , and Occidental Petroleum OXY.N gain between 2.3% and 2.7% - among the top percentage gainers on the energy index

** Diamondback Energy FANG.O up 1.6%, Devon Energy DVN.N gains 0.7% and Coterra Energy CTRA.N rises ~1%

(Reporting by Sumit Saha in Bengaluru)

((Sumit.Saha@thomsonreuters.com;))