Israel and Bulgaria have already accused the powerful Lebanese Shiite movement Hezbollah of being behind the attack at Burgas airport on the Black Sea, the deadliest on Israelis abroad since 2004.
Bulgaria had previously identified as alleged accomplices two Lebanese men with links to Hezbollah -- and with Canadian and Australian passports -- and has made so-far unanswered extradition requests to Lebanon.
Chief prosecutor spokeswoman Rumyana Arnaudova declined to comment on the latest report in the Pressa newspaper, which cited sources in the Bulgarian intelligence services.
The bomber died in the attack -- although it remains unclear if he intended to die -- and investigators had been unable to identify him despite having DNA from the severed head and limbs found at the site of the bombing.
Chief prosecutor Sotir Tsatsarov returned on Friday from a four-day visit to Israel where he met attorney general Yehuda Weinstein and chief prosecutor Shai Nitzan.