But the EU countries promised to abide by a 60-day waiting period before shipping any arms because of the possibility of Syrian peace talks next month and the desire to pressure President Bashar Assad's regime to be serious about negotiating, an official said.
The new support for Syria's outgunned rebels came hours after U.S. Sen. John McCain, R-Ariz., made a surprise visit to Syria, meeting with opposition leaders to reinforce his calls to arm moderate rebels.
It also came as U.S. Secretary of State John Kerry met with his Russian and French counterparts in Paris to explore prospects for a peace conference that would bring together opposition and Syrian regime officials.
"While we have no immediate plans to send arms to Syria, it gives us the flexibility to respond in the future if the situation continues to deteriorate and worsen," British Foreign Secretary William Hague told reporters after more than 12 hours of divisive talks in Brussels.
Countries such as Austria, the Czech Republic and Sweden strongly opposed arms shipments, saying the move could deepen the bloodshed and undermine next month's possible peace conference.
Both Britain and France, which have been pushing for months for the EU to relax its ban on sending weapons to the main moderate opposition group, promised they would supply weapons to the rebels only if they have strong assurances the arms wouldn't end up in the hands of extremist forces that have spread through rebel ranks, The Wall Street Journal reported.
But more than that, the EU countries that might decide to supply arms committed not to ship any weapons to Syria before Aug. 1, a decision intended in part to pressure the Assad regime into talks, a British official told the Journal.
"Lifting the embargo can accelerate peace talks, because the Syrian regime will have to negotiate," a French official told the newspaper.
In the end, the 27 foreign ministers were split on a vote to renew the arms embargo, so it will formally expire Friday.
The vote came several hours after McCain slipped into Syria through Turkey and met with opposition leaders for several hours, spokesmen for McCain and a key rebel alliance said.
McCain and the rebel leaders "discussed solutions to help remove" Assad, Free Syrian Army spokesman Louay al-Mokdad told The Washington Post.
"He was very open and promised to push for us with the U.S. administration," Mokdad said. "We asked about targeted strikes, and we briefed him about Bashar Assad's use of chemical weapons."
McCain told the leaders the international community "needs to take serious steps to help us," Mokdad told the Post. A McCain spokesman declined to provide details of the visit.
Meanwhile, Kerry, Russian Foreign Minister Sergei Lavrov and French Foreign Minister Laurent Fabius had a working dinner at a Paris restaurant Monday night to figure out how to make the peace conference in Geneva, Switzerland, a reality.
Syria has said it agreed "in principle" to attend the conference. But the fractious opposition has yet to say yes or no.
Washington and Moscow also have differences in who should be included in the conference. Lavrov pushed for the inclusion of Iran, a key backer of the Assad military, the Voice of America reported.
Kerry, Lavrov and Fabius agreed in their dinner meeting any use of chemical weapons in Syria would be a game-changer, officials said.
Before the dinner, Kerry said he and Lavrov, who met together earlier in the day, "expressed our mutual concerns about any potential use of chemical weapons and the need to really get the evidence and ascertain what has happened in that regard."
"Both Russia and the United States, if it were being used, would object to that very, very strongly," Kerry said.