European foreign ministers have been at odds during intensive talks on whether an arms embargo on Syrian rebels should be lifted.
Foreign Secretary William Hague clashed with his Irish counterpart, who insisted sending more weapons into the war-torn country would result in further casualties.
A defiant Mr Hague said discussions would centre on reaching agreement across the bloc on the contentious issue, but he would not rule out Britain's dissention.
Mr Hague said: "That's an option for the UK and France - both countries have said that - but our emphasis is on making sure we keep agreement in the EU. That's what we have been focusing on so far and we'll have discussions on that."
The UK and France have been vocal in their hopes of arming rebel forces. But Ireland was joined by Finland and Belgium in voicing its fierce opposition to the further militarisation of Syria.
Irish Foreign Affairs Minister Eamon Gilmore dashed any prospect of a pan-European agreement on arming rebels. The minister, who also serves as deputy prime minister, said more guns would lead to more casualties, and that EU ministers should focus on a political solution to the crisis.
The Tanaiste said: "I think further militarisation in Syria would certainly not be helpful. The more guns, the more arms that go into Syria, the more casualties there will be."
He said protecting civilians should be a priority and added: "We need to support a political solution, a peaceful solution, and we need to ensure that humanitarian aid will be permitted to be provided to the people of Syria."
Likewise, Belgian Foreign Minister Didier Reynders said his country would be "cautious" of any moves that would endanger more lives.
The Finnish minister added it was important that the EU states stick together on the divisive issue.