Mamat shot a 1-under 71 at Saujana Golf and Country Club to finish the 36-hole event at 7-under 137. Chia and Moir tied for second, two shots behind, to earn the other available British Open spots.
Americans Bryan Saltus and Peter Teravainen finished tied for eighth, seven shots behind Mamat.
This year's British Open will be held at St. Andrews, Scotland in July. Chia and Moir will make their major tournament debuts. Mamat competed in the British Open in 1997.
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