Datuk Seri Najib Tun Razak has condemned Tel Aviv for its aggression in the occupied territories, and called for a permanent end to injustice against the Palestinians.

The Prime Minister also spoke of the threat of the so-called Islamic State, which "knows nothing of Islam's noble ideals," and of Malaysia's own experience in curbing militant extremism.

Speaking at the 70th session of the United Nations General Assembly here Thursday, he said courage was needed to permanently address the injustice that the Palestinians had been suffering since 1948.

"Decades of impunity and the systematic dehumanisation of Palestinians have culminated in increasing violence, increasing illegal settlements, and increasing violations of rights. The frustration and anger felt by Palestinians resonates with Muslims worldwide.

"If the world continues to turn a blind eye to the Palestinians' sufferings, we risk another catastrophe in the Occupied Palestinian Territories. We will also fail to uphold the right to self-determination, which was at the very basis of the United Nations when it was created 70 years ago," Najib added.

On that note, given the Rosh Hashanah violations of Al-Aqsa Mosque in East Jerusalem and aggression against worshippers three weeks ago, he urged the Israeli government to "live up to Judaism’s highest ethical principles and the essential message of the Torah".

Najib said Israel had forced its authority over Islam’s third holiest site – in defiance of the jurisdiction of King Abdullah of Jordan, the lawful custodian.

"It is therefore Israel’s duty to facilitate Muslims from around the world to visit. For this is an aspiration that all devout Muslims harbour and pray to be able to realise in their lifetime," he said.

In recent weeks, clashes between Palestinian worshippers and Israeli forces were reported almost daily at the Al-Aqsa Mosque.

On Wednesday, for the first time in history, the Palestinian flag was raised at the United Nations headquarters, after the Palestinan Authority obtained non-member observer status at the UN in 2012.

On the Islamic State, Najib said Malaysia regarded seriously the problem of militants, both the people who wished to use Kuala Lumpur as a transit point and those wanting to sow violence and destruction at home.

"Much of this work cannot be revealed for security reasons. This may lead some to think that because Malaysia has not suffered from a successful terrorist attack, we do not have national security challenges. That is not the case. Our tireless, ever-vigilant security forces have intercepted many would-be IS recruits transiting through Kuala Lumpur.

"It is because of our efforts that they have not fallen into the darkness that blights Syria and Iraq. We have identified 39 Malaysians who have travelled to join IS. And we have arrested over 100 of our citizens suspected of links to IS," the Prime Minister said.

"We must strive harder to combat this threat together. Militaries and intelligence services need to share information, and countries need to collaborate more, daring to pre-emptively arrest as necessary."

Najib said the world must combat the Islamic State and its "warped ideology" that was theologically incoherent and a travesty of Islam, "which commands us to be knowledgeable, compassionate and humble".

"It is more important than ever that we spread awareness of authentic Islam. Islam unequivocally prohibits killing civilians during war. It explicitly protects minorities and respects those of other faiths. It urges the pursuit of knowledge, and stresses both justice and compassion," he added.

Najib said there should be no strife among Muslims, and not between Shia and Sunni, who may take different paths, but seek the same destination.

"The Malaysian Government has helped develop an important body of scholarship. An international group of Sunni and Shia scholars representing a cross-section of the global Muslim community was convened in Kuala Lumpur," he said.

He said the group's mission was to define an Islamic State, based on Islamic religious thought through the past 14 centuries, and it is nothing like the entity in Syria and Iraq that usurps that name.

"The scholars unanimously emphasised that an Islamic State must deliver justice in all its forms – political, economic and in the courts – to its citizens. It must be based on the objectives of Shariah, or Maqasid Shariah, which is to protect and enhance life, religion, intellect, property, family and dignity," he said.

Najib said the so-called Islamic State knows nothing of Islam’s noble ideals, of its compassion, or of the solemn duty to care for and learn about our fellow man.

"They are violating the Divine will. They are desecrating the name of our religion through their self-proclaimed caliphate – to which no true Muslim will pledge allegiance. This is the message we must spread, to Muslims and non-Muslims," the Prime Minister said.

"And I call on the Umma to rise with one voice, and let the world ring when we say to IS: You do not represent us."