The Bulgarian authorities are probing a possible terrorist attack on the motorcade of chief prosecutor Ivan Geshev that happened on May 1, the Ministry of Interior said in a statement.

The ministry’s chief secretary Petar Todorov said that the incident happened around 11:45 am, when an explosive device was set off on the road between city of Samokov and the village of Kovachevtsi, when Geshev’s motorcade was passing by. The explosion did not injure anyone.

The blast, next to Geshev’s car, contained at least 3 kg of TNT equivalent and multiple fragments, pellets the size of a human fingernail, almost cut down a tree by the road, Borislav Sarafov, director of the National Investigation Service, told reporters as quoted by Dnevnik news outlet.

Sarafov added that, according to witnesses, the explosion created a column of fire 4-5 metres tall, and the crater formed was 30-40 cm deep and 3 m in diameter next to the roadway.

"The explosion has a clear focus on the road, on the passing vehicles and is placed on a sharp turn where speed should be reduced," Sarafov said.

Although the explosion did not injure anyone, it moved Geshev’s car. According to Sarafov, Geshev was travelling to Sofia. He added that usually the routes of top officials guarded by the national security service are secret.

Sarafov said the initial information shows that the bomb attack aimed to kill someone and Geshev was lucky to survive. The perpetrators are believed to have manually triggered the blast from a distance, but close enough to see cars travelling on the road.

The interior ministry said the attack is a threat to national security, and all security services are working on investigation of the incident.

"A threat to the life of every Bulgarian citizen is unacceptable and our actions will be in defence of the health, life and property of Bulgarian citizens," Todorov said.

There were no suggestions as to who might have been involved in the alleged attack or why someone would want to harm Geshev.

The chief prosecutor has highly controversial reputation and his election has caused numerous protests at the time. He has been repeatedly accused of shielding politicians from Gerb and the Movement for Rights and Freedoms (DPS), while at the same time chasing their opponents.

Geshev has refused to investigate several major corruption scandals involving Gerb’s leader, former prime minister Boyko Borissov, and key members of DPS.