SINGAPORE, Feb 20 (Reuters) - China's Tibet Airlines on Tuesday signed an order for 40 C919 narrowbody jets and 10 ARJ21 aircraft from state-owned planemaker COMAC.

The two companies signed the deal at a ceremony on the sidelines of the biennial commercial and defence-focused Singapore Airshow.

The order comes after Tibet Airlines and COMAC in December announced that they would jointly research a variant of China's C919 jet suitable for high-altitude plateaus. (Reporting by Brenda Goh; Editing by Muralikumar Anantharaman)