SINGAPORE, Feb 20 (Reuters) - Royal Brunei Airlines has placed a firm order for four Boeing 787-9 Dreamliner planes for delivery from the second half of 2028, the carrier's chief executive said on Tuesday.

The order also includes purchase rights for two additional 787-9 aircraft, Royal Brunei CEO Sabirin Hamid said on the sidelines of the Singapore Airshow.

"We have had a lot of experience with Boeing already... so we want to keep with them," he said.

The airline has yet to decide which engine type it will purchase for the planes, he added. Rolls-Royce and GE both provide options for the model. (Reporting by Lisa Barrington in Singapore; Writing by Jamie Freed. Editing by Gerry Doyle)