Several countries have warned the EU against arming Syrian rebels, saying more weapons will lead to more deaths as the conflict spreads to neighbouring countries.

Canada's Foreign Affairs Minister John Baird said on Tuesday that there would be "more violence, more deaths and more destruction" in Syria if the EU goes through with allowing an arms embargo to expire on Saturday.

"My strong view is that the only way to end the suffering of the Syrian people is a political solution," he told reporters.

"Flooding the country and the region with more arms will lead to more violence, more deaths and more destruction, so certainly Canada has no intention of following suit," he said.

The EU agreed late on Monday to lift its embargo on arming the Syrian opposition after much debate and a strong push by France and Britain.

'Illegitimate' decision

Russia said the EU's decision was "illegitimate" and would harm peace efforts, while insisting that its own delivery of sophisticated missiles to Syria was a deterrence against foreign intervention.

"This in and of itself is a rather controversial decision because arms supplies to non-state entities are forbidden by international law," Foreign Minister Sergei Lavrov said.

"This is an illegitimate decision in principle," Russian news agencies quoted Lavrov as saying, one day after talks on the Syrian crisis in Paris.

His deputy Sergei Ryabkov added that the embargo "directly harms the prospects of convening an international conference".

The comments underlined the problems faced by Russia and the United States as they try to arrange a conference on ending bloodshed in Syria that Lavrov agreed to work towards with US Secretary of State John Kerry earlier this month.

Syria's government said arming the fighters is an "obstruction" to efforts to resolve the conflict in the country peacefully.

"The European Union's decision exposes ... its obstruction of international efforts to achieve a political settlement to the crisis in Syria," the foreign ministry said in a statement published by state news agency SANA.

Meanwhile, Iranian Foreign Ministry spokesman Seyyed Abbas Araqchi said the EU's decision was a "hasty and dangerous move".

Araqchi added that the EU has "definitely increased threats against themselves".

US support

Still, none of the block's 27 members have any immediate plans to send arms to the rebels.

The US said it backs the decision as a show of support for rebels fighting President Bashar al-Assad.

"While it is ultimately an EU decision, we do support the easing of the EU arms embargo as a part of the international community's efforts to demonstrate its full support for the Syrian opposition," State Department spokesman Patrick Ventrell said.

"It is helpful because it sends a message to the Assad regime that support for the opposition is only going to increase," Ventrell said, adding: "This gives the flexibility to specific EU member states to assist the opposition wherever each sees fit."

Meanwhile, the commander of the main Western-backed umbrella group of Syrian rebels said on Tuesday he was "very disappointed" that the embargo lifting would not lead to immediate weapons shipments.

Speaking by phone from Syria, General Salim Idris also told The Associated Press that the Lebanese group Hezbollah, an ally of the Syrian regime, has sent thousands of fighters to Syria and is emerging as the main threat to his Free Syrian Army, a coalition of rebel units.

He called for urgent international action to stop the influx of Hezbollah fighters, warning that if no action is taken, FSA fighters might ignore his standing order and start targeting the Shia group's bases in Lebanon.