BRUSSELS — Divisions among European Union foreign ministers on Monday prevented the renewal of the arms embargo on Syria, raising the possibility of a new flow of weapons to rebels fighting to bring down the government of President Bashar al-Assad.

“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,” William Hague, the British foreign secretary, said after more than 12 hours of stormy talks.

In a declaration, the European Union said member states that might wish to send weapons to Syrian rebels “shall assess the export license applications on a case-by-case basis” in line with the organization’s rules on exports of military technology and equipment.

The ministers did agree to renew all the economic sanctions already in place against the Syrian government.