A Bulgarian court has opened the trial of two men charged with terrorism for their alleged involvement in a 2012 suicide bombing that killed five Israeli tourists and their bus driver and injured 35.

Meliad Farah, a dual Lebanese-Australian national, and Hassan El Hajj Hassan, a dual Lebanese-Canadian national, will face trial in absentia as their whereabouts are unknown, the specialized criminal court announced Wednesday.

On July 18, 2012, Mohamad Hassan El-Husseini, a French-Lebanese national, blew himself up on a tourist bus at the airport in the Black Sea resort of Burgas.

The two men on trial are alleged to have provided the explosive device and logistical support to the bomber.

An investigation found that the attack was the work of the military wing of Hezbollah, leading the European Union to declare it a terrorist organization.

The trial will continue on Feb. 6.