“It is regrettable that Iran has yet to reach agreement with the IAEA on a plan to resolve all outstanding issues,” the spokesperson told a news briefing at UN Headquarters in New York.

According to media reports, a leaked quarterly report from the IAEA notes that Iran has doubled the number of uranium enrichment centrifuges it has in an underground bunker.

Meanwhile, Iran has also yet to allow the IAEA to visit a military site at Parchin, where the agency suspects Iran carried out explosives testing that it is now working to cover up, which has “significantly hampered” the agency’s investigation efforts.

The Iranian nuclear issue was a topic of discussion in the UN chief’s various meetings in Tehran, where he attended the 16th Summit of the Non-Aligned Movement (NAM). The Summit, under the chairmanship of the Government of Iran, in the Iranian and drew representatives from its 120 members, as well as from various associated observer countries.

Iran’s nuclear activities have been of international concern since the discovery, in 2003, that Iran had concealed its nuclear activities for 18 years, in breach of its obligations under the Nuclear Non-Proliferation Treaty. Iran has repeatedly stated that its nuclear programme is for the peaceful purpose of providing energy.

In a statement in the Tehran summit Iran’s Supremem leader said: “I stress that the Islamic Republic has never been after nuclear weapons and that it will never give up the right of its people to use nuclear energy for peaceful purposes.” But Israel, the United States and their allies in Europe  believe Iran is developing atomic weapons.

In a meeting on Thursday, with the Iranian Foreign Minister, Aliakbar Salehi, Mr. Ban had shared his concern about Iran’s nuclear programme and underscored the importance of transparency in this matter, as well as the need for Iran to fully comply with the IAEA.

He added that he has condemned threats by any Member State to destroy or delegitimize another. “And I have reminded leaders here – and indeed throughout the region – to lower the volume and stop the provocation that can lead this area down a slippery slope of conflict. It is time for more reason and responsibility,” Mr. Ban said.

Ban’s remarks come after Iranian remarks earlier this month threatening Israel’s existence. Iran’s president Mahmoud Ahmadinejad called Israel a “cancerous tumour” with no place in a future Middle East, were “outrageous and hateful” while Iranian media had earlier reported that Iran’s Supreme Leader Ayatollah Ali Khamenei had said Israel would one day be returned to the Palestinian nation and would cease to exist.

The Iranian remarks come as a series of Israeli media suggest that Israel could attack Iranian nuclear facilities ahead of U.S. presidential elections in November.

Mursi in his address in the summit in Iran attended by 120 nations spoke about the situation in Syria saying that “Our solidarity with the struggle of the Syrian people against an oppressive regime that has lost its legitimacy is an ethical duty as it is a political and strategic necessity,” Mursi added.

Mursi’s address to the Non-Aligned Movement summit in Tehran discomfited Syria’s Iranian backers and drew strong criticism from Syrian Foreign Minister Walid Muallem, who said the Egyptian president had broken the NAM tradition “by interfering in the affairs of Syria,” according to comments to Al-Alam channel.

Egypt’s state-run website Al-Ahram said Morsi’s address sparked a walkout by the Syrian delegation but Muallem said he only left the for the interview with Al-Alam TV before returning.

Mursi then spoke about the Palestinian Authority, saying that the Palestinian independence “has been a priority of the (Muslim Brotherhood) movement since its birth and it will be so until we achieve a comprehensive solution that will support the right of the Palestinian people to decide their own future and to establish their free state on their own soil,” AFP reported.

He emphasised in his speech the Palestinians’ “right to self determination and a free state” and voiced support for their bid to become full members of the United Nations.

Egypt’s ties with Iran deteriorated after the 1979 Islamic Revolution brought to power a theocracy that opposed Egypt’s peace treaty with Israel. As president, Mursi has so far refused to address the issue of whether ties would be upgraded with Iran, but has suggested he would pursue a more balanced foreign policy.