WASHINGTON — An Australian is among the suspects in a bus bombing that killed five Israelis and a driver in a Bulgarian resort last year, two Western officials said Tuesday.

The officials are familiar with the investigation and spoke only on condition of anonymity because they are not authorized to speak to the news media.

U.S. officials expect Bulgarian investigators to link the militant group Hezbollah to the July 18 attack in the coastal city of Burgas, in which a bomb ripped through a bus that was taking the tourists to their hotel. Bulgarian authorities are expected to release their findings on Tuesday.