A British request to blacklist the armed wing of Hezbollah ran into opposition in the European Union on Tuesday, with several governments expressing concern that such a move would increase instability in the Middle East.

Britain has argued that the militant Shi’ite Muslim group should face European sanctions because of evidence that it was behind a bus bombing in Bulgaria last July that killed five Israelis and their driver. Hezbollah denies any involvement.

London has also cited a four-year jail sentence handed down by a Cypriot court in March to a Hezbollah member accused of plotting to attack Israeli interests on the island.

Blacklisting the group would mark a major policy shift for the European Union, which has resisted pressure from Israel and Washington to do so for years.

But at a meeting in Brussels, convened to weigh the British request, several EU governments questioned whether there was sufficient evidence to link Hezbollah to the attack in Bulgaria, according to EU diplomats.

Some also reiterated concerns that such a move would complicate the EU’s contacts with Lebanon, where Hezbollah is part of the coalition government, and could increase turmoil in a country already suffering a spillover of civil war from Syria.

“The issue of political and security consequences” was raised, one EU diplomat said. More discussions on the issue will be held in Brussels in the next two weeks, with a decision possibly taken by the end of the month, diplomats said.

Already on the EU blacklist are groups such as Hamas, the Palestinian Islamist movement that rules the Gaza Strip, and Turkey’s Kurdish militant group PKK. Their assets in Europe are frozen and they have no access to cash there, meaning they are blocked from raising money for their activities.

The British proposal has gained urgency − and some support − in Europe in recent weeks amid signs that Hezbollah is increasingly involved in Syria’s largely sectarian bloodshed.

France has dropped objections to blacklisting the group, and said it had intelligence information that as many as 3,000-4,000 Hezbollah militants were fighting alongside the army of Syrian President Bashar Assad.

But others were more cautious. Italian Foreign Minister Emma Bonino has said her government needs more evidence from Bulgaria and is concerned for “the fragility of Lebanon”.

Bulgarian officials have countered that a recent reconstruction of events in connection with the Burgas bombing has confirmed evidence collected so far.