The Iranian and Saudi foreign ministers met Sunday in New York, with their rival states brought together by their opposition to the Islamic State jihadist group, the Iranian government said.

"This is a new page in relations between the two countries," Iran's Mohammad Javad Zarif said, quoted on the government's website.

Iran's judiciary has issued a one-month ultimatum for the government to ban applications WhatsApp, Viber and Tango, in a move that could boost existing restrictions on Internet use in the country.

Iran has a policy of filtering online content, which leaves popular websites such as Facebook, Twitter and YouTube inaccessible without the use of illegal software.

Washington's arch-foe Iran has a role to play in tackling Islamic State militants who have overrun large swathes of territory in Iraq and Syria, U.S. Secretary of State John Kerry said.

Iran's supreme leader Ayatollah Ali Khamenei said this week that his government had rejected a request from the United States for cooperation on the battlefield.

Authorities in Kenya said Friday they have arrested two men believed to be Iranian nationals transiting through the east African nation on fake passports.

A counter-terrorism officer told AFP the pair were detained on Thursday at Jomo Kenyatta International Airport, but that it was not yet established if the pair should be treated as terrorism suspects or illegal migrants.

The United States has discussed the threat posed by Islamic State militants with envoys from its traditional foe Iran on the sidelines of nuclear talks, the State Department revealed Friday.

"Discussion on this threat did arise on the margins of the meeting as they have from time to time," spokesman Jeff Rathke told reporters.

Washington urged Iran Thursday to engage with a stalled U.N. nuclear probe, saying it was crucial to a major accord under discussion between Iran and world powers this week in New York.

Laura Kennedy, the U.S. representative at the International Atomic Energy Agency (IAEA), said Washington was "concerned... by the pace of progress" in the Vienna body's investigation.

Iranian Foreign Minister Mohammad Javad Zarif hit out against the Islamic State group Wednesday as a "dangerous phenomenon," but warned it could not be defeated by air strikes.

Accusing other nations of having created "a Frankenstein that has come to haunt its creators," Zarif said at a Washington think-tank that the Islamic militants cannot be "eradicated through aerial bombardments," nor can they be contained.

As Iran and world powers prepare to resume nuclear talks, a new poll Wednesday revealed most Iranians back a deal but consider unacceptable some of the toughest demands to rein in their atomic program.

About 94 percent of Iranians said their country needed a nuclear energy program and seven in ten insisted that it was for peaceful purposes only.

Iranian President Hassan Rouhani will address the U.N. General Assembly in New York next week but is not scheduled to meet Barack Obama, a government spokesman said on Wednesday.

Rouhani's first major foreign visit as president was to last year's General Assembly, where he held a historic telephone call with Obama on the sidelines, the highest level contact between the two countries since Iran's 1979 Islamic revolution.

A senior Syrian official on Tuesday criticized the international community for excluding Damascus from recent talks on building a coalition to tackle the Islamic State group.

Deputy Foreign Minister Faisal Muqdad, quoted by state news agency SANA, expressed "astonishment" that Syria was not invited to the talks, which were attended by countries that Damascus claims fund "terrorism".