By Justyna Pawlak

BRUSSELS (Reuters) - The European Union will consider imposing sanctions on the Lebanese Islamist group Hezbollah but does not yet have sufficient evidence of its activities in Europe to make a decision, the European Commission said on Thursday.

Bulgaria in February implicated Hezbollah in a bombing in the Black Sea resort of Burgas last year that killed five Israelis, putting pressure on the EU to sanction the group.

Israel also has stepped up lobbying in Brussels and Paris, calling on European governments to follow the United States in listing the Shi'ite Muslim group as a "terrorist organization" and impose financial sanctions on it.

European Commission President Jose Manuel Barroso, speaking at a news conference with Israeli President Shimon Peres in Brussels, said Bulgaria was still finalizing its investigation into the attack and had asked the Lebanese government for help.

"The judicial process will show whether we should take political decisions. We cannot decide this in advance," Barroso said. "Once the perpetrators are known, their inclusion in the list ... may be considered."

Many European governments are cautious, arguing that imposing sanctions on Hezbollah could destabilize the government in Beirut and contribute to tensions in the Middle East. Hezbollah is a dominant force in Lebanese politics, with Prime Minister Najib Mikati relying on the group for support.

Peres warned that if the EU delayed in imposing sanctions on Hezbollah, it would only empower the group, whose military wing is involved in the conflict in Syria, where it is supporting the forces of President Bashar al-Assad.

"I hope that Hezbollah will be called to order," Peres said.

"If you don't take measures against Hezbollah, they may think they are permitted to do so."

A European diplomat close to the issue said on Wednesday one EU member state was expected to file an official request to blacklist Hezbollah's military wing in the next month.

"A request should be made within a month and be considered in two to three months," the diplomat told reporters, speaking on condition of anonymity. "It has become an overwhelming case."

In Europe, only the Netherlands has listed Hezbollah as a terrorist group, while Britain blacklists the group's military wing. A Dutch diplomat said the Netherlands had no intention of filing a formal request to list Hezbollah's armed wing.

"The Netherlands has pleaded since 2004 to include Hezbollah on the EU list of terrorist organizations and has consistently expressed that view to its EU partners. The Netherlands will continue its efforts to list (all) of Hezbollah," he said.

France and Germany have opposed similar moves, but diplomats say sufficient evidence from Bulgaria linking Hezbollah to the Burgas bombing could change that.

If the EU decides to add the militant movement, established nearly 30 years ago to confront Israel's occupation of south Lebanon, European governments and companies would have to cease any financial dealings with it.

(Reporting by Justyna Pawlak; Editing by Michael Roddy)