Bulgaria's foreign minister, Nikolay Mladenov, told CNN he presumes the explosion was a terrorist attack.

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Security Council to condemn the attack, perhaps Thursday, said Mladenov, who traveled to the blast scene.

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The head of the United Nations Assistance Mission for Iraq, Nickolay Mladenov, told reporters Wednesday that the warplanes that bombed the Iraqi cities were not Iraqi jets, but he did not have information beyond that.

CNN: ISIS right outside Baghdad

"If Bulgaria did not have enough arguments to announce yesterday that the traces in this attack lead to Hezbollah's military wing, we would not have done it, " Nikolay Mladenov told a TV station.

BBC: Hezbollah hits out after Bulgaria bus bomb report

During her official visit, the Director-General will hold meetings with the President of the Republic of Bulgaria Rosen Plevneliev, Prime Minister Boyko Borissov, Minister of Foreign Affairs Nikolay Mladenov, Minister of Culture Vezhdi Rashidov, Mayor of Sofia Jordanka Fandakova, as well as prominent Bulgarian intellectuals.

UNESCO: MEDIA SERVICES

Inaugurated by Irina Bokova, Director-General of UNESCO, in the presence of Abdou Diouf, Secretary-General of La Francophonie, Nickolay Mladenov, Minister of Foreign Affairs of Bulgaria, and Boutros Boutros-Ghali, former Secretary-General of the United Nations, the roundtable will include two thematic sessions which will allow participants to respond to political, social, cultural and educational challenges resulting from present and future social change.

UNESCO: Democracy and renewal in the Arab World: roundtable at UNESCO in support of transition to democracy, 21 June | United Nations Educational, Scientific and Cultural Organization