* Strong security presence on Iran's streets

* Obama "outraged" by crackdown

EDITORS' NOTE: Reuters and other foreign media are subject to Iranian restrictions on their ability to report, film or take pictures in Tehran.

By Parisa Hafezi

TEHRAN, June 24 (Reuters) - A security crackdown appears to have quelled street rallies against Iran's disputed poll, but the leadership faced a new challenge on Wednesday from calls by reformist clerics for national mourning for dead protesters.

While defiant cries of "Allahu Akbar" (God is greatest) were again heard from Tehran rooftops as darkness descended overnight, Iran's hardline Islamist leadership, for now at least, seemed to have gained the upper hand.

Hundreds of riot police and Basij militiamen on Tehran's main squares appeared to have largely put an end to mass protests against the June 12 election, which reformists say was rigged in favour of hardline President Mahmoud Ahmadinejad.

At least 10 protesters were killed in the worst violence on Saturday, and about seven more early last week. Many of the deaths have been filmed by fellow demonstrators, posted on the Internet and viewed by thousands around the world.

U.S. President Barack Obama toughened his stance on Tuesday and said he was "appalled and outraged" by Iran's crackdown.

Iran has accused the protesters of being backed by the West, the United States and Britain in particular, and have paraded arrested young demonstrators on state television confessing to being incited by foreign news broadcasts.

The Foreign Ministry accused U.N. Secretary-General Ban Ki-moon of interfering in Iran's affairs "under the influence of some powers", an apparent reference to Britain and the United States.

MOURNING Tehran's hardline leadership is locked in a dispute with Western powers over its nuclear programme, which it says is intended for generating electricity but which the West suspects could yield nuclear weapons that could destabilise the region.

Obama said the United States would not interfere in the protests, describing accusations it was instigating them as "patently false and absurd".

"This tired strategy of using old tensions to scapegoat other countries won't work any more in Iran," he said.

Grand Ayatollah Hossein Ali Montazeri, a dissident but yet one of the most senior clerics in Iran, called for three days of national mourning from Wednesday for those killed.

"Resisting the people's demand is religiously prohibited," Montazeri said in a statement on his website.

Montazeri was once named successor to Ayatollah Rohullah Khomeini, but fell out with the founder of the Islamic Republic shortly before his death in 1989. Montazeri has been under house arrest in the holy city of Qom for around a decade.

Reformist cleric Mehdi Karoubi who came third in the election also signalled opposition would continue, calling on Iranians to hold ceremonies on Thursday to mourn the dead.

But in an apparent concession, Supreme Leader Ali Khamenei, who holds all the key levers of power in Iran, accepted a request from Iran's top legislative body to allow five more days for candidates to lodge complaints over the election.

The 12-man Guardian Council though has already rejected demands for a vote re-run from moderate former Prime Minister Mirhossein Mousavi, who says he is the rightful victor. (Writing by Jon Hemming; Editing by Ralph Gowling)

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