European Union foreign ministers on Monday stopped short of meeting Britain's demand to lift an arms embargo on Syria but agreed to allow "non-lethal" aid and "technical assistance" to flow to the opposition.

"We would've gone further, some were against. This is a compromise," said British Foreign Secretary William Hague at the close of talks with his 26 EU counterparts. "We will return to it in three months."

After weeks of "divisive" talk on whether to arm Syria's rebels, the ministers in a lengthy session agreed to renew sanctions against President Bashar al-Assad until the end of May that notably bar the supply of any lethal weaponry to the country -- regime or rebel.

But this was while "amending them so as to provide greater non-lethal support and technical assistance for the protection of civilians," an EU statement said.

The ministers would again "assess and review, if necessary, the sanctions regime" after three months, it added.

Hague said details on goods or expertise -- such as trainers, helmets or protective clothing -- likely to flow to Syria would be issued in the coming days, and EU foreign policy chief Catherine Ashton said legal experts would ensure the change was in line with common policy.

"It's not about military support," said Ashton. "It's about how to make sure to give the best possible support to the protection of civilians."

Hague however said the agreement to amend the arms embargo "establishes an extremely important precedent."

The bloc's wide-ranging measures against Syria, including the arms ban but also targeting scores of Assad cronies and regime-friendly firms, as well as oil, trade and finance, expire at the end of the month.

Their renewal requires unanimity.

French Foreign Minister Laurent Fabius, whose country along with Italy offered London some backing, said Monday's decision showed "extra support" for the Syrian National Coalition (SNC) fighting the Assad regime and a response to a request for aid from SNC leader Ahmed Moaz al-Khatib.

"The decision's in line with France's position. So I'm very pleased," he said.

Hague on arrival had called for changes to the existing arms ban "so that we can provide a broader range of support to the National Coalition."

"We give them strong political and diplomatic support. We also give them assistance in terms of equipment at the moment to help them try to save people's lives," he added. "I think there is a broader range of equipment that we could give to them."

But Britain found little support with only days left before the deadline to renew the sanctions expired.

"I don't see any need to amend the embargo, I don't think it would make sense to send more weapons to Syria," said Austria's Michael Spindelegger, echoing counterparts from Cyprus, Sweden and Spain.

Even Ashton, a British baroness who represents London on the European Commission, appeared opposed.

"Delivering arms might bring about a new military balance on the ground," said an internal paper on the matter drafted for the member states by her service.

"But it could also fuel further militarisation of the conflict, increase risks of dissemination among extremist groups and of arms proliferation in a post-Assad Syria," said the paper.

"Broadly speaking any EU decision allowing arms transfer to the opposition should take into account obligations under international law as well as EU Treaty and principles," the paper added.

Sweden's Carl Bildt had underlined the ill timing of any such move, saying the EU should "concentrate the maximum support" on current efforts to push a political settlement."

UN peace envoy Lakhdar Brahimi was supposed to attend Monday's talks but had to pull out as efforts mount to make good an offer from al-Khatib to negotiate with some regime figures.