A suicide bomb attack has killed at least 11 Iraqis and injured dozens of coalition soldiers at a Polish army base at Hilla, officials say.
The blast ripped through several houses near the base
A coalition spokeswoman said the dead included women and children and the toll was expected to rise as bodies were pulled out of damaged buildings.
A lorry laden with about 700kg of explosives blew up after ramming into another vehicle at the perimeter.
The coalition says 58 soldiers and 44 Iraqi civilians were injured.
A Polish logistical base called Camp Charlie was targeted, about 100 km (60 miles) south of Baghdad, at 0715 (0415GMT) on Wednesday.
Four homes near the base reportedly collapsed in the blast.
First one vehicle smashed into the base's fence and troops on guard opened fire, killing the driver, a Polish military spokesman said.
The lorry then rammed it and blew up, the spokesman told the BBC.
The injured soldiers included at least 12 Filipinos, 10 Hungarians, 10 Poles and an American, officials said.
Several nearby buildings were damaged and the military are searching the rubble for casualties and survivors.
Spate of bombings
Polish General Mieczyslaw Bieniek called it a "well-coordinated terrorist attack".
Poland commands a multi-national force of about 9,500 soldiers in south-central Iraq. Its troops also fought in the US-led war that toppled Saddam Hussein.
The BBC's Jonny Dymond in Baghdad says coalition bases are now heavily fortified, but the latest bombing shows that the insurgents are still a serious threat to them.
Poland spearheads a multinational force in Iraq
The Hilla attack came a week after two suicide vehicle bombings - against an Iraqi police station in Iskandariya and an army recruiting centre in Baghdad, which killed about 100 Iraqis.
A Polish officer was killed in an attack in Iraq last November.
In the same month, a truck bomber killed 19 Italians and 13 Iraqis in an attack against an Italian police camp in the southern city of Nasiriya. It was the worst attack on a US ally since the occupation began.