Arab League Secretary-General Nabil Elaraby speaks during a news conference after the closing session of the Arab Summit in Sharm el-Sheikh, in the South Sinai governorate, south of Cairo on 29 March 2015. Arab leaders at a summit in Egypt announced the formation of a unified military force to counter growing security threats from Yemen to Libya and as regional heavyweights Saudi Arabia and Iran engage in sectarian proxy wars REUTERS/Amr Abdallah Dalsh

Plans to form a joint Arab defence force to tackle Iranian-backed Shi'ite rebels in Yemen were unveiled at the end of a two-day summit, with Arab leaders vowing to crush the rebels.

The joint force would be deployed at the request of any Arab nation facing a national security threat and to combat terrorist groups, said the summit resolution.

The chiefs of staff of the Arab League will meet within a month and would have an additional three months to work out the details to be presented at a meeting of the league's Joint Defense Council.

The defence force would consist of up to 40,000 elite troops backed by jet fighters, warships and light armour and would be headquartered in either Cairo or Riyadh, according to Egyptian military.

The joint force proposal comes alongside the Iran nuclear deal, which is expected to be finalised by Tuesday, wherein UN sanctions against Iran would be lifted in return for a restriction of its nuclear programme.

Saudi Arabia and its Gulf allies fear that the nuclear deal will bolster Iran's influence in the region.

While Arab leaders at the summit made veiled references to the threat to the Arab identity being posed by "foreign" or "outside parties", the Arab League chief, Nabil Elaraby, was unequivocal during a news conference where he singled out Iran for its intervention "in many nations".

Iran has in recent years consolidated its hold in Iraq, Syria, Lebanon and now Yemen.

"Yemen was on the brink of the abyss, requiring effective Arab and international moves after all means of reaching a peaceful resolution had been exhausted to end the Houthi coup and restore legitimacy," Elaraby said, reading from the final communique.

Airstrikes to continue

He said the Saudi Arabia-led air campaign would continue until all Houthi militia withdraw and surrender their weapons and a strong unified Yemen is in place.

Airstrikes hit Houthi targets throughout Sunday, including ammunition depots, and heavy weapons and vehicles the rebels had taken from government forces, according to AP.

The Saudi intervention has come as a surprise as the conservative monarchy has not often displayed its military might. It is expected that the strikes could continue for a month or even more.

The Houthis captured Yemen's capital, Sana'a, in September. They are believed to be supported by Iran and Hezbollah.

Embattled Yemeni President Abed Rabbo Mansour Hadi first fled to the southern city of Aden before fleeing the country last week.

Speaking at the summit on Saturday, Hadi accused Iran of being behind the Houthi offensive.

Iran and the Houthis deny the charge but acknowledge that the Islamic Republic is providing humanitarian and other aid.

A possible ground invasion could follow once the airstrikes that began on Thursday weaken the Houthis and their allies.

Yemen's foreign minister, Riad Yassin, said the air campaign, code-named Operation Decisive Storm, had prevented the rebels from attacking Yemeni cities or Saudi Arabia with missiles. It also stopped Iran's supply line to the rebels, he said at a news conference on Sunday.

Meanwhile, military officials are not ruling out Iranian retaliation. Iran has condemned the airstrikes but so far has taken no any military action.