Prime Minister Najib Abdul Razak needs to speak out against US President Donald Trump's anti-Muslim tweets, Pakatan Harapan leaders said.

"The prime minister should at least speak out. What is the use of meeting Trump if you don't use your good ties to speak out against his Islamophobia," Amanah vice-president Mujahid Yusof Rawa told Malaysiakini.

PKR secretary-general Saifuddin Nasution, meanwhile, said Najib's silence on the matter "is not an option".