Europe's foreign ministers began last-ditch attempts in Brussels yesterday to avoid the collapse of sanctions against Bashar Al Assad's Syrian regime amid divisions on whether arms should be supplied to rebels.
A flurry of diplomatic activity, which also drew US and Russian officials to separate talks in Paris, coincided with fresh reports of chemical weapons being used by the Al Assad government against its opponents.
The French foreign minister, Laurent Fabius, said there were "mounting suspicions" that chemical weapons were being used in Syria but that "very detailed verification" was necessary.
"We are consulting with our partners to examine what concrete consequences to draw," Mr Fabius added as ministers of the 27-member European Union met in the Belgian capital.
The French daily newspaper Le Monde said a correspondent and photographer had witnessed several attacks this month and in April near Damascus. The photographer was said to have suffered respiratory difficulties and blurred vision after one incident.
Le Monde's report follows what a BBC report earlier this month called "unverified footage" of civilians hit by an apparent chemical attack in the town of Saraqeb.
The current EU arms embargo, which expires at midnight on Friday, affects the opposition Syria National Coalition as much as the Damascus government.
Britain and France want the sanctions to be eased so that the rebels can be armed. But this is opposed by several EU countries. The aid agency Oxfam predicts "devastating consequences", fanning the flames of conflict, if the sanctions policy is allowed to collapse.
But Britain and France believe improving the opposition's means of self-defence, and by implication giving it greater power in attack, would help force Damascus to recognise it had to negotiate a political solution. London and Paris insist this must include Mr Al Assad standing down as president.
Austria, along with the Czech Republic, the Netherlands, Finland and Sweden, is against arming the rebels. Other countries, such as Germany, are unconvinced.
There are fears among some countries that any weaponry provided to the rebels could later fall into the hands of Islamist extremists involved in the anti-Assad fighting and likely to prove hostile to western interests. For these countries, the example of post-Qaddafi Libya is hardly encouraging.
If ministers fail to agree on relaxing the embargo, one possibility is that they will allow the present arrangement to continue unamended until next month, when the US and Russia hope to bring together the government and opposition for direct talks in Geneva.
Another option, according to a BBC report, would be some military equipment to be sent to Syria, but with strict conditions attached.
Meanwhile, the US secretary of state, John Kerry, was in the French capital last night for talks with France and Russia's foreign ministers, Mr Fabius and Sergey Lavrov, about the planned peace talks, called Geneva 2. The Al Assad regime had said it agreed "in principle" to attending the meeting.
The British foreign secretary, William Hague, said before the Brussels meeting that "standing still" was not an option.
"Most of the world denies [the opposition] the means to defend themselves, so that is creating extremism, radicalising people," he said. "We are reaching the limits of how long we can go on with that situation."
Doing "the right thing for Syria" was more important than the EU's wish to agree on every detail, he said.
Mr Hague said there was ultimately only a political and diplomatically supported solution but stressed that modifying the arms embargo was "part of supporting the diplomatic work".
In Geneva yesterday, the US, Turkey and Qatar persuaded the United Nations Human Rights Council to hold another debate on the civil war in Syria, the first such session in more than a year, as diplomats pushed for more international pressure to hold accountable those responsible for killing thousands of civilians.
The council president, Remigiusz Henczel, said the debate would be held tomorrow, and officials said negotiations had already begun on a resolution focused on the violence in the Syrian town of Qusayr, close to the border with Lebanon.
Syrian troops backed by fighters from the Lebanese Shiite militant group Hizbollah continued their assault to recapture the strategically important town yesterday after more than a year of rebel control.
Activists groups said regime forces had captured the nearby town of Hamidiyeh, tightening the siege on Qusayr.
* With additional reporting from Associated Press