Malaysian Prime Minister Najib Razak. Pic: AP.

KUALA LUMPUR, Malaysia (AP) — Malaysian leader Najib Razak is suing an independent online news portal for allegedly defaming him and his ruling Malay party.

The action against Malaysiakini is believed to be the first by a Malaysian prime minister against a media organization. Rights activists called it a threat to press freedom.

The news portal said on its website that it received legal papers Tuesday accusing it of publishing readers’ comments that defamed Najib and damaged his image. The comments were critical of Najib and questioned alleged corruption in his party.

Malaysiakini editor Steven Gan said Najib was offered a chance to reply but refused. Gan said the news portal, known for criticisms of the government, would fight the suit vigorously.

Najib lodged the suit after Malaysiakini refused to apologize and retract the comments.