BAGHDAD, 13 September 2004 — Fifty-two people, including three Polish soldiers, were killed and scores wounded in a fresh surge of violence in Iraq yesterday. Twenty-five of them died in Baghdad as insurgents pounded the capital with one of their most intense mortar barrages in the heart of the capital ever.

Thirteen people were killed when a US helicopter fired at Iraqis celebrating the destruction of a Bradley fighting vehicle on Haifa Street. The four tank crewmen escaped with minor injuries.

Another 12 people died and 41 were injured in other violence across the city, Health Ministry official Saad Al-Amili said.

A suicide attacker detonated an explosives-packed vehicle just outside Abu Ghraib prison, killing himself but causing no other casualties, the US military said. American guards fired at the vehicle as it sped toward the front gate, the military said.

Abu Musab Al-Zarqawi’s Tawhid wal Jihad claimed responsibility for the attacks in an Internet statement. The group said it held the initiative in the insurgency and possessed the “capability to surprise the enemy and hit its strategic installations at the right time and place.”

US Lt. Col. Steve Boylan said that from late Saturday to early yesterday, more than a dozen mortar rounds and rockets were fired into or around the Green Zone.

The three Polish soldiers were killed and three others wounded in an ambush near the Shiite city of Hilla, the Polish military said.

Also in the area, three national guardsmen were killed and three wounded in a double bomb attack. West of Baghdad, 10 people were killed and 40 wounded as insurgents and US soldiers clashed in Ramadi, a medic said. North of Baghdad, in the flashpoint Sunni city of Samarra, five Iraqis were killed when an apparent suicide bomb intended for US convoys blew up, said police. Further north in Mosul, five policemen were killed and 10 wounded in two separate gun attacks, medics said.

Meanwhile, militants threatened to kill two Italian female hostages if Rome did not recall its troops from Iraq within 24 hours. Italy said it was sending Foreign Minister Franco Frattini to the Middle East.