( AP ) - A series of mortars or rockets slammed into the U.S.-controlled Green Zone on Thursday, and an official said at least one round struck a parking lot used by the Iraqi prime minister and his security detail.
The barrage occurred a day after the U.S. military acknowledged "an increasing pattern of attacks" against the sprawling complex on the west bank of the Tigris River despite a security crackdown now in its fifth month.
A huge plume of black smoke billowed into the sky and helicopters buzzed overhead after about nine blasts occurred in quick succession around 10 a.m.
At least one mortar round struck a parking lot used by Prime Minister Nouri al-Maliki and his security detail, an official from the prime minister's office said. The official spoke on condition of anonymity because he wasn't authorized to release the information.
The U.S. Embassy confirmed there were rounds of indirect fire, the military term for rockets or mortars, but said it could not immediately provide details such as where they struck.
A recent increase in mortar and rocket attacks on the Green Zone, which houses the American Embassy and major Iraqi government offices, has raised new concern about the security of thousands of U.S. soldiers and foreign contractors, as well Iraqis.
It was unclear whether the rounds were fired by Sunni or Shiite extremists. Both groups operate in areas of the city within rocket and mortar range of the heavily fortified complex of concrete buildings and checkpoints.
Mortar and rocket crews can set up their weapons quickly on the beds of trucks or in parts of the city with limited surveillance, fire their rounds and flee before U.S. and Iraqi forces can respond.
A June 5 U.N. report said insurgents had bombarded the Green Zone with rockets and mortar fire more than 80 times since March, reportedly killing at least 26 people.
Rear Adm. Mark Fox, a U.S. military spokesman in Baghdad, declined to provide details on the number of attacks against the Green Zone, which is also known as the International Zone, but said they were increasing.
"It's clear that there is an attempt to get lucky shots, and there is unquestionably an increasing pattern of attacks here against the International Zone. There's no doubt about that," Fox said Wednesday at a joint news conference with Iraqi military spokesman Qassim al-Moussawi.
Al-Moussawi said the attacks were coming from inside residential areas, causing difficulties in responding to them because of concern about civilian casualties.