Two individuals with links to Lebanon's militant group Hizbollah were involved in a bomb attack on a bus in the Bulgarian resort of Burgas that killed five Israeli tourists last July, Bulgaria's Interior Minister said.

The conclusions of the Bulgarian investigation may open the way for the European Union to join the US in branding the Iranian-backed Hizbollah a terrorist organisation since there is now a clear connection to an attack on EU territory.

Three people were involved in the attack, two of whom had genuine passports from Australia and Canada, Tsvetan Tsvetanov said yesterday after Bulgaria's national security council discussed the investigation.

The group is believed to have arrived in Burgas a month before the bombing.

Mr Tsvetanov added: "We have established the two were members of the militant wing of Hizbollah. There is data showing the financing and connection between Hezbollah and the two suspects."

Israel blamed the attack in the Black Sea city – which killed five Israeli tourists, their Bulgarian driver and the bomber – on Iran and Hizbollah, a powerful Shi'ite Islamist militia that is part of the Lebanese Government.

Tehran has denied responsibility and accused Israel of plotting and carrying out the blast. Hizbollah has not publicly responded to charges by Israel and US agencies it played a role.

The Netherlands said in August the EU should follow the lead of the US, which designated Hizbollah as a terrorist organisation in the 1990s, a move that would enable the EU to freeze Hizbollah's assets in Europe.