Arab nations that normalised ties with Israel last year have “sinned” and should reverse such moves, Iran’s supreme leader Ali Khamenei said on Sunday. The United Arab Emirates, Bahrain, Sudan and Morocco all agreed to normalise ties with Israel in 2020, as Washington under the administration of then US president Donald Trump made Arab-Israeli rapprochement a foreign policy priority. “Some governments have unfortunately made errors — have made big errors and have sinned in normalising (their relations) with the usurping and oppressive Zionist regime,” Khamenei said, referring to Israel. “It is an act against Islamic unity, they must return from this path and make up for this big mistake,” Khamenei added, in a speech marking a public holiday honouring the birth of the Prophet Mohammed. Iran has in the four decades since the 1979 Islamic revolution positioned itself as a strong defender of the Palestinian cause. Egypt and Jordan were until last year the only two Arab countries to normalise relations with Israel. “If the unity of Muslims is achieved, the Palestinian question would definitely be resolved in the best fashion,” Khamenei said. In May, Khamenei characterised Israel as a “terrorist base” and “not a country”. Shortly after Khamenei’s speech, Iran’s top security official, Ali Shamkhani, vowed to inflict many “billions of dollars” worth of damage in a “shocking response” if Israel strikes Tehran’s nuclear programme. The tweet by the secretary of Iran’s Supreme National Security Council came in response to Israeli media reports that five billion shekels ($1.5 billion) had been approved to prepare the military for a potential strike on Iran’s nuclear programme. Iran has repeatedly accused Israel of being behind acts of sabotage targeting its nuclear facilities. The two countries have exchanged sharp rhetoric recently, against the backdrop of efforts to renew talks to revive a nuclear deal between Iran and world powers.