By Georgina McCartney and Arathy Somasekhar

HOUSTON, May 11 (Reuters) - A cargo of crude oil loaded from the U.S. Strategic Petroleum Reserve is heading to Turkey, the first shipment of U.S. emergency reserve oil to the Mediterranean country, ship tracking data showed.

The U.S. is in the process of releasing 172 million barrels from the SPR in a bid to combat spiking crude prices, as the war in Iran has upended global supplies with the critical chokepoint, the Strait of Hormuz, remaining largely closed. The move is part of a coordinated effort by the International Energy Agency to release a record 400 million barrels of oil to quell rising prices.

Exports from the U.S., the world's largest producer, have touched record highs as supplies across Europe and Asia have tightened, sending prices higher.

Greek-flagged aframax North Star loaded around 680,000 barrels of sweet crude from the Bryan Mound strategic petroleum reserve site near Seaway, Texas City in April and is set to arrive in Aliaga, Turkey, in mid-May, Kpler data showed, citing a bill of lading.

And Hong Kong-flagged DHT Antelope loaded about 1.1 million barrels of Bryan Mound Sour crude oil at offshore Galveston through ship-to-ship transfer in late April, and is also due to unload in Turkey at the end of the month, according to ship tracking data and a trader. The ship also carried another parcel of U.S. crude, Kpler data showed.

U.S. SPR cargoes have already headed to Italy and the Netherlands, according to ship tracking data.