BANGKOK, June 9 (Reuters) - A fire has damaged a diesel-making unit at the 215,000 barrels-per-day Rayong plant operated by Thai refiner IRPC, the company's chief executive told Reuters on Monday.

The fire has been brought under control, said IRPC chief executive Sukrit Surabotsopon in a telephone interview.

"The fire broke out at the preparation area to supply feedstock to a diesel cracking unit," he said. "We don't know how much damage there has been. We are assessing it."

(Reporting by Pisit Changplayngam and Khettiya Jittapong; Writing by Simon Webb)

((Simon.Webb@thomsonreuters.com; +6626489757; Reuters Messaging: simon.webb.thomsonreuters.com@reuters.net))

Keywords: THAILAND REFINERY/FIREFIGHTERS