Prime Minister Najib Abdul Razak has been asked to explain the reasons behind a decision by Saudi Arabian Oil Co (Saudi Aramco) to pull out of its US$27 billion (RM119.64 billion) joint venture with Petronas in Pengerang, Johor.

"It appears to be a sudden decision (by Saudi Aramco) to withdraw from the project.

"So the main issue here is, why did they pull out?" Parti Amanah Negara deputy president Salahuddin Ayub told Malaysiakini.