* GS Caltex to buy 920,000 barrels of West African crude
* First West African shipment in almost a year
* Vessel chartered by Unipec (Adds GS Caltex comment, clarifying volume it will receive)
By Jacob Gronholt-Pedersen and Meeyoung Cho
SINGAPORE/SEOUL, June 12 (Reuters) - South Korea's GS Caltex Corp is set to receive its first shipment of West African crude in almost a year as the country looks to diversify supply away from the Middle East.
The purchase will help soak up a glut of supply among West African producers, who have been hit as the U.S. shale oil boom curbs demand in what was once their main market and as OPEC Gulf states boost supply.
Middle Eastern producers have raised their selling prices to Asia in recent months following solid demand in that region, prompting some buyers to try to broaden their sources of supply, with GS Caltex already turning to Mexico for crude.
GS Caltex, South Korea's second-biggest refiner, is due to receive 920,000 barrels of crude from West Africa that is being shipped on the Very Large Crude Carrier (VLCC) New Frontier, a spokesman said.
The vessel, currently southeast of Madagascar, loaded nearly 2 million barrels of crude in Angola and Congo Republic late last month and is expected to arrive at South Korea's Yeosu port on July 1, according to Reuters shiptracking data.
GS Caltex last took West African crude in August 2014.
The buyer of the remaining crude on the vessel was not clear. Reuters could not confirm the price and grade of the crude being shipped.
The New Frontier was chartered by China's Unipec, the trading arm of state-owned Sinopec. A Sinopec spokesman declined comment.
South Korea has imported an average of just over 500,000 barrels of West African crude per month over the last two years, or less than 1 percent of total import volumes, according to Reuters data.
The cargo was purchased in April during the normal trading window, so it is unlikely to be one of the numerous unsold West African shipments that have drawn market attention, according to a person familiar with the deal. He declined to be identified as he was not authorised to speak to the media.
China and India have also emerged as large buyers of West African crude in recent years.
Although Angola and Congo Republic are not generally considered to be in West Africa, oil markets categorise crude from those countries as West African.
GS Caltex this year bought oil from Mexico for the first time in 25 years, while Hyundai Oilbank Co Ltd signed a deal with Mexico's state oil firm Pemex to take 5 million barrels of crude in the second half of 2015. (Editing by Joseph Radford and Alan Raybould)