The bomb that exploded last summer at Bulgaria's Sarafovo airport near the Black Sea city of Burgas has been made with two to three kilos of trinitrotoluene, TNT.

Insider sources from the investigation, speaking off-the-record, have told the Bulgarian National Radio that all expert reports on the terror act have concluded.

The final details such as the exact position of the bomber at the time of the explosion will be established by the reenactment scheduled for April 26 at the Ihtiman training ground, when two buses with dummies as passengers will be blown up.

According to some witness accounts, the bomber attempted to put the explosives in the bus' luggage compartment, while others say he stood near the door.

The explosive will be made by the Interior Ministry's Technical Operations Directorate, SDOTO.

On July 18, 2012, Bulgaria's Black Sea city of Burgas became a target for a terrorist attack.

The bus explosion killed a total of five Israeli tourists, the Bulgarian bus driver, and the alleged perpetrator of the attack.

After the bombing, Israel was quick to throw the blame for the attack on Hezbollah and Iran.

On February 5, 2013, following a meeting of the Consultative Council for National Security at the President's Office, then-Interior Minister Tsvetan Tsvetanov made a statement, saying that the investigating authorities had gathered evidence pointing to a "reasonable assumption" about the involvement of Hezbollah's military wing in the Burgas bus bombing.