NEW YORK, July 9 (Reuters) - U.S. Gulf Coast grades firmed on Thursday, dealers said, as concerns over Middle East supply disruptions intensified after Iran attacked U.S. military sites in Gulf states.

Prices were also buoyed by a Reuters report which said that governments were set to buy millions of barrels of oil through 2028 to rebuild emergency reserves depleted by drawdowns to plug a gap in global supply caused by the Iran war.

Replenishing those reserves could add up to 664,000 barrels per day of demand by third-quarter 2027, according to commodities analytics firm Kpler.

Light Louisiana Sweet, the Gulf Coast benchmark and a key export grade, strengthened on Thursday, as did Mars crude, a grade widely used by Asian refineries.

• Light Louisiana Sweet for August delivery firmed 50 cents to a midpoint of a parity and was seen bid and offered between a discount of 20 cents​​ and a premium of 20 cents a barrel to U.S. crude futures CLc1

• Mars Sour firmed 50 cents to a midpoint of a $2 discount and was seen bid and offered between a discount of $2.20 and $1.80 a barrel to U.S. crude futures CLc1 ​

• WTI Midland eased 15 cents to a midpoint of a 10-cent discount and was seen bid and offered between a discount of 30 cents​​ and a premium of 10 cents a barrel to U.S. crude futures CLc1​

• West Texas Sour eased 40 cents to a midpoint of a $2.35 discount and was seen bid and offered between a $2.65 and $2.05 a barrel discount to U.S. crude futures CLc1

• WTI at East Houston , also known as MEH, traded between a 5-cent and 25-cent a barrel premium to U.S. crude futures CLc1

• ICE Brent September futures LCOc1 fell $1.72 to settle at $76.3 a barrel on Thursday​.

• WTI August crude CLc1 futures fell $1.44 to settle at $72.08 a barrel on Thursday​.

• The Brent/WTI spread narrowed 34 cents to last trade at minus $4.41, after hitting a high of minus $4.28 and a low of minus $5.17.