Constitutional law expert Abdul Aziz Bari has urged the Sultan of Pahang to break his silence on the state mufti's use of the term 'kafir harbi' on non-Muslims who allegedly oppose Islam.

This is because a mufti is directly under the authority of the sultan, who must sanction his rulings as the head of the Islamic religion in the state, said Aziz.

"The Sultan of Pahang needs to break his silence on the matter.

"Even though this is not a federal matter it has become a national concern and therefore the Conference of Rulers needs to weigh in as well," he said.

He added that the rulers have a duty to show leadership because they have the power to do so.

He also argued that the 'kafir harbi' remark was a personal view and not a fatwa (edict) or ruling.

"Be that as it may, a sermon (khutbah) text that demonised DAP was also issued in Pahang some time ago.

"Is this a mere coincidence? Whatever it is, this provides more reason for the Sultan of Pahang to ease the tension," added Aziz, who sits on the Selangor DAP committee.

Pahang mufti Abdul Rahman Osman was reported in Utusan Malaysia last Friday as calling DAP 'kafir harbi' for opposing PAS' move to implement hudud in Kelantan through its president Abdul Hadi Awang's Private Member's Bill.

However, Rahman later told Malaysiakini that his statement was not only directed at the DAP but all those who opposed Islam.

In response to the public outcry against his statement, Rahman yesterday defended his stand and refused to apologise.

His critics have pointed out that pronouncing someone as 'kafir harbi' is a serious matter as it is meant specifically for those who are said to wage war against Islam and purportedly permits those so labelled to be slain.