An extremist Shiite group believed responsible for the killing of five American soldiers in a bold raid south of Baghdad and the kidnapping of five British men has agreed to renounce violence, a government adviser said Monday.

The deal was reached during a weekend meeting between Prime Minister Nouri al-Maliki and representatives of Asaib Ahl al-Haq, or League of the Righteous, a group the U.S. alleges is backed by Iran and refuses to adhere to a militia cease-fire.

The group promised to lay down its weapons and join the political process, according to government aide Sami al-Askari, who was at the meeting. In return, al-Maliki promised to seek the release of the detainees in U.S. custody, al-Askari said.

The deal comes as the Shiite-led Iraqi government moves increasingly to assert its sovereignty and solidify its power base ahead of national elections scheduled for January. The U.S. military also has seen its influence wane as it begins to pull back its troops with plans for a full withdrawal by the end of 2011.

The transformation of the remaining Shiite militant groups into political organizations would be a significant development for Iraq as it prepares for the end of the U.S. military role. It also could boost Tehran's leverage in the neighboring country, although Iran's government denies any links to Shiite extremists in Iraq.

Iraqi politicians with links to the Asaib al-Haq have said the group wants to participate in next year's parliamentary vote, either by fielding its own ticket or backing candidates from other Shiite parties.

Government spokesman Ali al-Dabbagh also confirmed the deal, according to Iraqi state television.

"The delegation of the Asaib Ahl al-Haq group announced its support for the political process, renounced violence and offered support for efforts to achieve national unity," he told reporters. "Both sides agreed to solve the pending problems, especially the issue of detainees whose hands have not been stained with Iraqis' blood and who have no criminal evidence against them."

Several high-profile Shiite detainees have been released from American custody this summer, including key Asaib al-Haq member Laith al-Khazali in June. He and his still-detained brother, Qais, were accused of organizing a daring attack on a local government headquarters in Karbala that killed five U.S. soldiers on Jan. 20, 2007.

The U.S. military has been freeing inmates or transferring them to Iraqi custody as part of a security pact that took effect on Jan. 1.

Al-Khazali's release was widely believed to be part of negotiations for the release of five British hostages captured two years ago in a raid on Iraq's Finance Ministry that was blamed on the group.

However, the bodies of two of the kidnapped contractors were found and returned to England earlier this summer, and Britain said last week that two others were likely dead. The IT consultant the contractors had been guarding, Peter Moore, is believed to be alive.

A cease-fire called by anti-U.S. cleric Muqtada al-Sadr after his forces were routed in American-backed Iraqi government offensives has been a key factor in ebbing the rampant sectarian violence that pushed the country to the brink of civil war.

But Asaib Ahl al-Haq and other Shiite extremist factions broke with al-Sadr, raising fears that the bloodshed could resume.

The group's main liaison with the government, Salam al-Maliki, said only that many issues were discussed.

"The Iraqi government is getting its full sovereignty on Iraqi land, especially after signing the security pact and accelerating the withdrawal of American troops from Iraq," he told state television.

The Shiite militia cease-fire, along with a Sunni revolt against al-Qaida in Iraq and a 2007 U.S. troop buildup have led to a sharp decline in attacks nationwide. But a series of recent bombings has raised fears that violence could resurge.

A suicide car bomber struck a police checkpoint Monday in Saqlawiyah, west of Baghdad, killing at least three people and wounding seven in the seventh attack in Anbar province in two weeks. A total of 24 people have been killed in the series of bombings that began on July 20.

Provincial security official Sheik Efan Saadoun blamed political rivalries for destabilizing the situation and said the Americans pulled back too fast. The U.S. military maintains a presence in the region and has said it is ready to help if requested.

"We lack the military and the security power they enjoy in controlling movement at the main security checkpoints in addition to their sophisticated detection instruments," Saadoun said. "We were extremely dependent on the Americans in this field."

In other violence reported by police Monday, roadside bombs killed two Iraqi soldiers and wounded four others in separate attacks in the northern city of Mosul. Bombs also exploded on two buses leaving the mainly Shiite city of Hillah, killing two people and wounding 25 south of Baghdad.

Separately, Iraq said it has arrested a man suspected of killing a well-known Iraqi TV journalist who was abducted while covering the Feb. 22, 2006 bombing of a Shiite mosque north of Baghdad.

Atwar Bahjat of the Dubai-based Al-Arabiyah and two colleagues were abducted while covering the bombing in her hometown of Samarra that set off years of sectarian violence. Their bullet-riddled bodies were found the next day outside the city, north of Baghdad. All three were Sunni Arabs, but the station has a reputation as being critical of Iraq's Sunni insurgency.

Iraqi military spokesman Maj. Gen. Qassim al-Moussawi confirmed the arrest but provided no other details.

Journalists have frequently been targeted or caught up in Iraq's violence.

The New York-based Committee to Protect Journalists has recorded 139 journalists and 51 media support workers killed since the March 2003 U.S.-led invasion.