Iran’s supreme leader lashed out during a pro-Palestinian gathering in Tehran on Tuesday, calling Israel a "fake" nation in a "dirty chapter" of history.

The remarks by Ayatollah Ali Khamenei were some of his most vitriolic against Israel, Iran’s archenemy. Every four years since the early 1990s, Tehran has hosted a similar conference in support of the Palestinian cause, assembling foreign guests and those who oppose Israel.

Speaking to the gathering, Khamenei said Israel was created by bringing Jews from other parts of the world to the Mideast region to settle in the land of the Palestinians to replace its “true entity.”

The creation of Israel is “one of the dirty chapters of history that will be closed, with the grace of God,” he added. Khamenei’s speech lasted 33 minutes.

The supreme leader, who has final say on all state matters in Iran, also urged all Muslims to support the Palestinians and “resistance” movements — a reference to anti-Israeli militant groups such as Palestinian Hamas and Lebanon’s Shite Hezbollah militants. Iran has always been their staunch ally.

The “resistance movements should have all necessary instruments,” Khamenei added and praised those who are part of it in allegedly succeeding in “preventing the domination of the Zionist regime in the entire region.”

But he did not appear to endorse an all-our war on Israel, saying instead that it’s a “cancerous tumour” that requires a “step by step” treatment. In 2015, Khamenei predicted that Israel would not exist after 25 years.

Some 80 delegations, mainly from Islamic countries as well as pro-Palestinian activists, attended the two-day meeting. Iranian President Hassan Rouhani and several government officials also attended the conference.

The venue was decorated with a large map of Israel and the Palestinian territories covered in the colours of the Palestinian flag.

Since the 1979 Islamic Revolution, which ousted the pro-western Shah Mohammad Reza Pahlavi and brought the Islamists to power, Iran has not recognized Israel and has supported anti-Israeli groups.

Israel, which seas a nuclear-armed Iran as an existential threat, has opposed the 2015 landmark deal between Iran and world powers that capped Iran’s nuclear activities in return for lifting sanctions.