Baghdad, Dec. 8 (Reuters): A suicide bomber killed 30 people and wounded at least 25 on a Baghdad bus today, in a bloody escalation of Iraq’s insurgency a week before elections.

The second major suicide bombing in the capital in three days, after a lull of several weeks, snapped attention back onto Iraq’s sectarian tensions after the theatre of Saddam Hussein’s trial this week.

It came a day after President George W. Bush applauded the progress in the reconstruction of Iraqi cities like Najaf and Mosul, and as kidnappers holding four western hostages extended a deadline to kill them by 48 hours.

Police said the crowded public bus was about to leave the Nahda bus station in central Baghdad for the southern Shia city of Nassiriya when the attacker got on board and detonated a vest packed with explosives.

Firefighters pulled charred bodies from the wrecked bus and loaded them into waiting ambulances as police tried to restore order around the site of the blast. “I was standing near when the blast happened,” one man said as he stood in front of the mangled wreckage, adding he had seen some passengers who survived with injuries. “All the remaining people inside the bus were killed,” he said.

In August, the central Baghdad bus station was hit by three car bombs, one of which tore through a bus destined for Basra, also in the predominantly Shia south.

Today’s bombing was the latest in a seemingly relentless insurgency led by Sunni Arabs, once dominant under Saddam, and foreign fighters against the Shia and Kurdish-led government and its US backers.