David Cameron: Syria empowering new al-Qaeda generation
David Cameron has warned there was a "strategic" as well as "moral imperative" to act as the death toll in Syria mounts.
The prime minister told MPs: "Syria is attracting and empowering a new cohort of al-Qaeda-linked extremists".
He also saw a growing risk of "drawing regional powers into direct conflict".
The PM said European leaders had agreed, at their recent summit, on the need to review the arms embargo to help opponents to President Bashar al-Assad.
Mr Cameron said: "A humanitarian crisis is unfolding in Syria on our watch, with over 40,000 dead and millions in need of urgent assistance as a hard winter approaches.
"We continue to encourage political transition from the top and to support the opposition which is attempting to force a transition from below.
"This should include and will include looking at the arms embargo. We must now explore all options to support the opposition to enable greater support for the protection of civilians."
He said there a "strategic imperative to act" because "Syria is attracting and empowering a new cohort of al-Qaeda-linked extremists".
He added: "There is a growing risk on instability spreading to Syria's neighbours, and a risk of drawing regional powers into direct conflict."
"We cannot go on as we are. Assad's regime is illegitimate, the council committed to work for a future for Syria that is democratic and inclusive with full support for human rights and minorities."
Following further questions about Syria from Labour leader Ed Miliband, Mr Cameron added: "It is right to look at amending the arms embargo; of course, we will be keeping the arms embargo on the regime.
"There are arguments on both sides of the debate but it is a debate that should be had, that European foreign ministers will be having.
"My concern is that if we, with others, aren't helping to shape and work with the opposition, it's much more difficult to get the transition we all want to see to a peaceful, democratic Syria that respects the rights of minorities."
Mr Cameron's statement to MPs on last week's gathering of European leaders came on the day Syrian Vice-President Farouq al-Sharaa said neither the government's forces nor the rebels can win the 21-month-old conflict.
Tens of thousands of Syrians have lost their lives in the escalating conflict between forces loyal to President Assad and those opposed to his rule.