DUBAI, Aug 1 (Reuters) - Qatar's Barwa Real Estate BRES.QA , one of the Gulf Arab state's largest listed developers, said on Monday it had bought a vacant plot of land in Riyadh, Saudi Arabia, for 659.28 million riyals ($175.8 million).

It did not give the name of the seller of the 2.22 million square metre plot. It said the deal was part of Barwa's plan to explore potential real estate investment opportunities in the kingdom and that the project would include residential and commercial use. ($1 = 3.7503 riyals)

(Reporting by Tom Arnold; editing by Susan Thomas) ((Tom.Arnold@thomsonreuters.com; +97144536265; Reuters Messaging: tom.arnold.thomsonreuters.com@reuters.net))