The suicide bomber who killed five Israeli tourists and a Bulgarian bus driver in the Bulgarian city of Burgas last Wednesday spoke Russian fluently, according to a local media report.

A taxi driver who drove the suicide bombing suspect from the town of Ravda to the town of Pomorie has claimed that he spoke Russian.

The taxi driver in question has declined invitations to talk to the media.

However, some of his colleagues have reported his statement to the Burgas24.bg news website.

On Monday, reports surfaced that Bulgarian police are investigating the involvement of two more accomplices involved in the deadly July 18 bus bombing at the airport in the resort city of Burgas.

Israel has said it suspects Iran or an Islamist militant group such as Hezbollah is behind the attack, a claim that has added to tension between Israel and Tehran. Iran, which has condemned the attack, has rejected Israel's claims.