European Union foreign ministers are to discuss British and French calls for them to ease sanctions against Syria so weapons can be supplied to the rebels, BBC News reports.
At a meeting in Brussels, UK Foreign Secretary William Hague is expected to argue that the current sanctions regime, which is due to expire at the end of this week, is no longer working.
He wants it amended so arms can be sent to "moderate" forces in the opposition.
However, several EU states are totally opposed to ending the arms embargo.
Earlier, Syria's foreign minister confirmed the government would "in principle" attend an international peace conference which the U.S. and Russia hope will take place in Geneva next month.
Walid Muallem said it would be "a good opportunity for a political solution" to the conflict, which the UN says has left more than 80,000 people dead.
Members of the main opposition coalition are currently discussing whether to attend the conference, but spokesmen have said they would if President Bashar al-Assad agreed to step down.
Hague has argued that partially lifting the EU arms embargo, so that weapons could be given to rebel groups, would complement, rather than work against, the peace process because it would strengthen the opposition's hand in negotiations with President Assad.
Last week, he told British MPs that weapons would be supplied only "under carefully controlled circumstances" and with clear commitments from the opposition.
"We must make clear that if the regime does not negotiate seriously at the Geneva conference, no option is off the table," he said. "We have to be open to every way of strengthening moderates and saving lives rather than the current trajectory of extremism and murder."
On Monday, May 27, Hague and the French Foreign Minister, Laurent Fabius, will urge other European governments to amend the embargo text to allow weapons to be supplied to the National Coalition for Syrian Revolutionary and Opposition Forces, or allow more assistance to be sent.
Another possibility is for the existing embargo, which expires at midnight on May 31, to be extended without amendment for a short period to see if the Geneva conference is successful.
