The European Union is moving closer to declaring the military wing of the Lebanese party Hezbollah a terrorist organization and could make a decision as soon as Monday if the last few countries with reservations are swayed, a senior EU official said Friday.

Such a possibility highlights a steady change of heart within the EU, which has long held back against U.S. pressure over fears such a move would destabilize Lebanon and its neighbors.

EU foreign ministers looked into the issue earlier this year, but could now reach a decision at their monthly meeting Monday, the official said. Putting an organization on the terrorist blacklist needs unanimity among the 28 member nations.

The official, who spoke on condition of anonymity because he was not allowed to speak publicly, would not name the countries still opposed to the move.

The Iranian-backed group Hezbollah plays a pivotal role in Lebanese politics, dominating the government since 2011. The official said diplomatic efforts by Lebanon could affect the decisions of some member states.

Even if the EU blacklists the military wing, the bloc wants to maintain contact with Lebanese political parties. Assurances of political outreach are essential to any terror blacklisting and have been instrumental in tipping the balance, according to three officials who said they were forbidden from speaking publicly on the issue ahead of Monday's ministerial meeting.

The senior EU official said the ministers will consider the listing based only on evidence that Hezbollah was involved in a 2012 attack in the Black Sea resort of Burgas in Bulgaria, which killed five Israeli tourists and one Bulgarian last year. Hezbollah denies it is responsible.

The discussion is also fueled by a Cyprus criminal court decision in March finding a Hezbollah member guilty of helping to plan attacks on Israelis on the Mediterranean Island.

Implementation of the listing would be complicated because diplomats would have to unravel the links between the different wings within Hezbollah's organizational network and see who could be targeted with visa bans or asset freezes.