Destroyed buses are seen at Burgas airport, outside the Black Sea city of Burgas, Bulgaria, some 400 kilometers (250 miles) east of the capital, Sofia, Wednesday, July 18, 2012. (AP Photo/ Bulphoto Agency)
SOFIA, Bulgaria (AP) — Bulgaria's prime minister says a sophisticated group of conspirators were involved in the suicide bombing that killed five Israelis and a Bulgarian bus driver, and that they spent a month in the country before the attack.
Boiko Borisov spoke alongside visiting U.S. Homeland Security Adviser John Brennan on Tuesday.
He says those involved used "leased vehicles, they moved in different cities so as not to be seen together, and no two of them can be seen in one place on any security camera."
But Borisov did not say how many people were believed involved in the Wednesday attack. He also declined to back up Israel's claims that Iran and militant group Hezbollah played roles.
Brennan also stopped short of blaming Iran or Hezbollah, both of which are U.S. nemeses.
Copyright 2012 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.