Former Sabah chief minister Yong Teck Lee must vacate his Gaya parliamentary and Likas state assembly seats since the Federal Court dismissed his appeal against the ruling which found him guilty of breaching the Election Offences Act.

Dewan Rakyat Speaker Mohamed Zahir Ismail said today that, section 48(4) of the Federal Constitution specifically stated that an elected representative found guilty of such an act by a court would lose his seat 14 days after the judgment was made.

"Therefore the 14 days deadline is Sept 17. If by then there are no changes, he will cease as Gaya MP on Sept 18," said the speaker when asked to comment on the matter.

Mohamed Zahir said there was no necessity for him to declare the seat vacant on Sept 18 as the process of law would take its natural course.

Asked if a by-election will be called, he said that has to be decided by the Election Commission.