Armed gunmen have launched an attack on the Abu Ghraib prison in Iraq, hitting the facility with rocket-propelled grenades and mortars, officials say. Twelve people were killed in the attacks.

The attackers hit the facility on the western outskirts of Baghdad late on Sunday night, as well as another prison in Taji, north of the capital.

The interior ministry said soldiers, police and attack helicopters had been dispatched to the prison to end the fighting and rioting by prisoners.

Three soldiers and a police officer were killed at Abu Ghraib, along with three of the attackers; while at Taji prison, five people were killed, including two soldiers and an inmate.

Al Jazeera's Jane Arraf, reported from Baghdad, said the attacks appeared to have been staged in an attempt to free prisoners.

"[Abu Ghraib prison] is now home to several high-ranking al-Qaeda prisoners, as is the prison in Taji," she said.

Series of bombings

The Islamic State of Iraq, the umbrella group for al-Qaeda in Iraq, has launched several similar raids in the past, aimed at freeing comrades being held in Iraqi prisons.

Elsewhere in Iraq on Sunday, bombings and shootings killed at least 13 people, as the death toll from a co-ordinated wave of late-night car bombings and other attacks the day before jumped past 70, authorities said.

The explosions and prison raids were the latest in a relentless surge in bloodshed that has rocked Iraq since the start of the Muslim fasting month of Ramadan on July 10.

The deadliest of Sunday's attacks came in the afternoon, when gunmen attacked a checkpoint manned by the Kurdish security forces known as Peshmerga near Kirkuk, killing five Peshmerga fighters.

The oil-rich city of Kirkuk is 290km north of Baghdad.

During Ramadan, streets are often filled with people out shopping and relaxing in cafes in the evenings, suggesting the attackers aimed to hit as many civilians as possible.

As the scale of the carnage from earlier bombings became clearer on Sunday, police reported that a total of 11 car bombs went off in Baghdad late on Saturday.

More than 2,700 people have been killed in Iraq since the beginning of 2013, according to AFP figures based on security and medical sources.