Insurgents pressing a campaign of violence in Iraq ahead of next month's constitutional referendum have killed five more people Friday in a suicide bombing at a Baghdad bus terminal.

Authorities say at least eight other people were hurt in the blast on a city bus.

The attack comes a day after Iraq's most influential Shi'ite cleric, Grand Ayatollah Ali al-Sistani, urged his supporters to vote "yes" in the October 15 national referendum.

In Washington, Saudi Arabia's foreign minister warned Thursday that Iraq is hurtling toward disintegration. Prince Saud al-Faisal told reporters he does not believe elections or a constitution alone will bring Iraqis together.

He said if Iraq is split into Shi'ite, Sunni and Kurdish states, it could drag other countries in the region into the conflict.

Some information for this report provided by AFP and AP.