Syria's opposition called for "sophisticated" arms at an Arab summit in Kuwait while Saudi Arabia said the military balance needed to change to "end the impasse" in Syria's civil war.
But UN-Arab League peace envoy Lakhdar Brahimi insisted on the need for a "political solution" to the three-year conflict, urging an "end to the supply of arms to all parties."
Opposition Syrian National Coalition chief Ahmed Jarba repeated calls on the international community to supply rebels with "sophisticated weapons" as the two-day summit opened on Tuesday.
"I do not ask you for a declaration of war," said Jarba, urging Arab leaders to put pressure on world powers to fulfil pledges to supply arms.
Saudi Crown Prince Salman bin Abdulaziz, whose country is a key backer of the rebellion against President Bashar al-Assad, said the world was "betraying" rebels by failing to arm them and leaving them as "easy prey."
A solution to the conflict, in which regime forces have recently made significant advances, requires a "change in the balance on the ground to end the impasse," he said.
National Coalition spokesman Louay Safi said rebels urgently needed "anti-aircraft missiles" to defend against barrel bombs that regime forces have been raining down on fighters and civilians alike.
The conflict in Syria, which entered a fourth year on March 15, has killed more than 146,000 people and displaced millions.
Meanwhile, Jarba said a decision not to hand over Syria's seat in the Arab League to the opposition sends a wrong message to Assad, telling him to continue "to kill."
"Let me say quite frankly that keeping Syria's seat empty... sends a clear message to Assad that he can kill and that the seat will wait for him," he said.
The government's brutal repression of protests that erupted in March 2011, which led to the war, resulted in its suspension from the 22-member Cairo-based Arab League.
- No military solution: Brahimi -
Brahimi urged a revival of peace talks.
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"I call upon Europe, the United Nations and the United States to take clear steps to reactivate the Geneva talks," which broke off on February 15.
"There is no military solution," he stressed.
On the humanitarian front, the president Lebanon, one of several Syrian neighbours dealing with refugees, told the evening session his country was overburdened by the influx and called for help.
Michel Sleiman said Lebanon was no longer capable of accepting more Syrian refugees. who now make up 32 percent of the population.
He warned without elaborating that, if Beirut does not receive help, "we may look into legal ways to stop their influx."
Meanwhile, a regional rift over Egypt's Muslim Brotherhood has been kept off the summit agenda.
But Egyptian President Adli Mansur called for interior and justice ministers meet before the end of June to activate the Arab counter-terrorism treaty.
Mansour made no specific mention of the Muslim Brotherhood of his ousted predecessor Mohamed Morsi, which Cairo designated a terrorist organisation in December.
But he told the summit it was vital that League members extradite and not give shelter to "terrorists" wanted by fellow member states. That was a veiled reference to Qatar, accused of harbouring fugitive Brotherhood leaders.
Relations between Egypt and Qatar have nosedived since the army's overthrow of Morsi last July.
And Qatar's support for the Brotherhood has strained ties with fellow Gulf states -- Bahrain, Saudi Arabia and the United Arab Emirates -- who withdrew their ambassadors from Doha earlier this month.
Kuwait's emir, Sheikh Sabah al-Ahmad al-Sabah, told the summit these rifts are threatening Arab aspirations and insisted that "we are required to resolve these disputes... and achieve unity."
But Kuwaiti foreign ministry undersecretary Khaled al-Jarallah said the dispute would "be resolved within the Gulf house," not at the summit.
On the Palestinian issue, Arab leaders are expected to call for $100 million (72.5 million euros) in monthly aid for the Palestinian Authority and to reject demands by Israel that Palestinians recognise it as a Jewish state.
Palestinian leader Mahmud Abbas, fresh from talks with US President Barack Obama in Washington last week, told the summit that Palestinians "reject even discussing the issue."
He warned of Israeli plans to divide Jerusalem's Al-Aqsa Mosque, highly revered by Muslims worldwide, between Jews and Muslims "which we totally reject."