By Adrian Croft and John Irish
BRUSSELS/PARIS (Reuters) - France will urge other European Union governments at a summit on Thursday to lift an embargo on supplying weapons to the Syrian opposition, President Francois Hollande said, saying Europe could not allow the Syrian people to be massacred.
Hollande justified his call to increase European help to the Syrian opposition after a two-year uprising against President Bashar al-Assad by saying that weapons were being delivered to Assad's government, particularly by Russia.
"We want the Europeans to lift the arms embargo - not to go towards a total war, we think a political transition must be the solution for Syria - (but) we must accept our responsibilities," he said as he arrived for a two-day EU summit in Brussels.
"France must first convince its European partners. But we ... cannot allow a people to be massacred as it is being today," he said.
France and Britain have stepped up calls to lift the arms embargo to permit supplies to the Syrian opposition to level the playing field in a conflict that has cost 70,000 lives.
But other EU governments, including Germany, have resisted the move, fearing it will fuel violence in the region.
Hollande and British Prime Minister David Cameron met separately at the start of the summit and agreed they would discuss with other leaders what more the EU could do on the Syria embargo, Cameron's spokeswoman said.
"What we want to do is inject some political momentum from the highest level of government across the EU into the discussions," she said.
The arms embargo was "backfiring", she said. "It doesn't stop those aiding Assad, it does stop EU countries and others helping those against whom Assad is waging a brutal and terrorising war," she said.
Britain and France hope the threat of arming the rebels will force Assad into talks and a transition of power.
United Nations aid chief Valerie Amos said an end to the arms embargo could complicate the humanitarian situation in Syria.
"Any more proliferation of arms and any more fighting is going to make our job more difficult," she told Reuters in Ankara. "Any kind of increase in the intensity of the fighting, what it will have is an impact on ordinary people."
French Foreign Minister Laurent Fabius said earlier that France and Britain wanted an urgent EU meeting, possibly this month, to persuade their allies to lift the embargo on supplying arms to the Syrian opposition.
Following Britain's line, Fabius warned that Paris could break with the EU embargo. That could pave the way for arms supplies to rebels.
The arms ban is part of a package of EU sanctions on Syria that rolls over every three months. An extension agreed last month expires on June 1. Without unanimous agreement to renew or amend it, the embargo lapses, along with the sanctions.
EU foreign ministers are to meet next informally on March 22 in Ireland and formally a month later. Depending on events in Syria, Paris and London will push for an emergency meeting before then to decide on the embargo, the source said.
Asked on France Info radio whether France and Britain would arm the opposition if there was no agreement, Fabius said only that France was "a sovereign state" and that the two countries would jointly act "to lift the embargo".
Turkish Foreign Minister, Ahmet Davutoglu, whose country is a fierce critic of Assad and harbours Syrian refugees and rebels, backed Fabius' comments.
"If the international community displayed in a very clear and decisive manner the will to stop the Syrian regime waging war, there would be no need for any kind of arming," he said.
Echoing comments by Russia, which has protected Assad from any U.N. measures, Syria's state news agency SANA said arming rebels would be a "flagrant violation of international law".
Western diplomats say Iran has significantly increased military support to Assad in recent months, solidifying its position alongside Russia as the government's lifeline.
After weeks of wrangling, Britain last month won EU agreement to relax the embargo to allow non-lethal but quasi-military aid to the opposition, such as armoured vehicles.
German Foreign Minister Guido Westerwelle said in a statement Berlin was ready to discuss the embargo.
"If important partners in the European Union now think the situation has changed and they think this makes it necessary to change the decisions on sanctions, we are of course prepared to discuss this in the EU immediately," he said.
A senior French official who spoke on condition of anonymity said anti-aircraft missiles were among weapons that might be supplied to already identified groups of rebel fighters.
(Additional reporting by Jonathon Burch in Ankara, Erika Solomon in Beirut, Julien Ponthus, Justyna Pawlak and Peter Griffiths in Brussels, and Michelle Martin in Berlin; Editing by Alistair Lyon and Michael Roddy)