Hezbollah, which is close to Iran, is Israel's sworn enemy, and its recent intervention in Syria has dismayed Western powers who back rebels battling to oust President Bashar al-Assad.
A decision to place the militia on the European Union list of terrorist groups requires approval by all 28 national ministers and it will take time, if agreed, to proceed to actual sanctions.
The EU seeks to play a leading role in the Middle East peace process and on Friday foreign affairs chief Catherine Ashton warmly welcomed news that US Secretary of State John Kerry had got Israel and the Palestinians to resume peace talks.
"There are still some reservations ... But we are moving towards a decision on listing Hezbollah's military wing," a senior EU official said Friday as Lebanon warned that such a move could potentially destabilise the fragile country.
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The official stressed that a decision would be fully justified by Hezbollah's involvement in an attack against Israeli tourists in Bulgaria last year and its activities in Cyprus.
But it would "not impact current EU policy and engagement with Lebanon," the official said, arguing that only the military wing would be targeted and not Hezbollah's political side, which was part of the outgoing Lebanese government.
Several EU member states have expressed sharp reservations over blacklisting it precisely because of such fears, but EU sources believe the consensus is now to go ahead.
"We would be surprised if some ministers stood in the way of the EU taking robust action on terrorism," another senior EU official said. "They'll need to think quite carefully before blocking consensus."
Asked if Hezbollah's intervention in support of Assad in Syria had changed opinion, the first senior official insisted this was "another issue completely."
EU sources said Syria and Egypt, which Ashton visited recently to press the need to uphold democratic reforms, will both be discussed today.