Our Team



Datin Yap Siew Bee (also known as Datin’ Mah Siew Bee) graduated with a Bachelor of Laws (Hons) degree from the University of Singapore and was admitted to the Malaysian Bar in 1974.

Prior to joining the firm as a Partner in August 1982, Datin’ Mah worked as a lawyer with a Kuala Lumpur based law firm and thereafter served as a Legal Advisor to Petroliam Nasional Berhad (“Petronas”).

While at Petronas, she garnered extensive experience in advising on legal matters relating to the oil and gas industry and established strong industry contacts. The firm was retained by Petronas to advise them on their new domestic and international ventures and projects and Datin’ Mah advised Petronas on a diverse range of oil and gas matters, including joint venture and project documentation, project financing matters, Engineering Procurement and Construction (EPCC) tenders and contracts, construction contracts, technology transfer contracts, proprietary (technology and licensing) agreements, procurement matters, sales/marketing and distribution agreements, feedstock agreements, engineering and technical support/training agreements, shipping agreements, insurance documentation and other related matters.

Datin Mah has advised, through the firm, on some of the most significant oil and gas and petro-chemical projects in Malaysia, including the setting up of the BASF-Petronas petrochemical complex in Kuantan, Pahang, Petronas’ petrochemical joint venture with Union Carbide and the MLNG One and MLNG Two projects which involved the construction of the largest LNG production facility in the world.

As part of her diverse practice, Datin’ Mah has also handled matters on behalf of the firm involving commercial ventures such as mergers and acquisitions of private and public listed companies, corporate finance transactions, due diligence exercises, corporate restructurings and joint ventures. She also has extensive experience in advising on banking and finance matters and real and personal property transactions, including corporate loans, loan syndications and loan restructurings.

Datin Mah has formerly served as an Independent Non-Executive Director of Petronas and also as the Non-Executive Chairman of Prince Court Medical Centre.  She is currently a member of the Board of Trustees of RHB Foundation.