(Raises death toll, adds details)
BAGHDAD, Sept 24 (Reuters) - A suicide bomber killed 26 people including the police chief of the Iraqi city of Baquba on Monday in a mosque compound where local Shi'ite and Sunni Arab leaders were holding reconciliation talks.
Two other senior police officers were killed while tribal leaders were among 50 people wounded in the attack in the local capital of Diyala province. Police said there were reports the governor of Diyala had also been wounded.
The attack bore the hallmarks al Qaeda, which has said it was launching a new round of attacks to mark the holy fasting month of Ramadan. The group has specifically warned it would attack tribal leaders cooperating with the security forces.
The bomber entered the compound while senior police officers, local government officials and tribal leaders were taking part in reconciliation talks and attending a meal to mark the breaking of the daily fast, police said.
The negotiations were aimed at easing tensions in the city, 65 km (40 miles) north of Baghdad.
Iraqi state television said members of the 1920 Revolution Brigades, a large Sunni Arab insurgent group, were among those taking part in the talks.
Separately, Iraq said no action would be taken against U.S. security firm Blackwater over a shooting in which 11 people were killed until after a joint investigation with U.S. officials.
Prime Minister Nuri al-Maliki had vowed to freeze the work of Blackwater, which guards the U.S. embassy in Baghdad, and prosecute its staff over the shooting eight days ago which he called a crime. But Iraq has since appeared to soften its stand.
Police named the dead police chief in Baquba as Brigadier-General Ali Dulayyan. Two other police brigadier-generals were killed.
Diyala is the scene of U.S. offensives to combat al Qaeda in Iraq militants who had overrun parts of the province.
Also on Monday, a suicide truck bomber killed six people on the road between northwestern Tal Afar and Mosul in the country's north, police said.
An al Qaeda-led group, the Islamic State in Iraq, has threatened a fresh wave of attacks in Ramadan.
It has claimed responsibility for the killing this month of Sheikh Abdul Sattar Abu Risha, the leader of a Sunni Arab tribal alliance in western Anbar province which joined forces with the U.S. military to drive al Qaeda out of much of that vast region.
A sustained campaign of violence would undermine U.S. and Iraqi assertions that a seven-month security crackdown had disrupted the Sunni Islamist network's operations in and around Baghdad while also reducing attacks from other groups.
IMMUNE FROM PROSECUTION
The shooting involving Blackwater angered many Iraqis, who see the thousands of private security guards working in Iraq as private armies who act with impunity, immune from prosecution under an order drafted after the 2003 U.S.-led invasion.
Government spokesman Ali al-Dabbagh said Blackwater's future would rest on the outcome of a joint inquiry by Iraqi and U.S. officials into the conduct of private security companies.
The U.S. embassy is conducting a separate inquiry into the circumstances of the shooting, in which Blackwater guards are accused of opening fire without provocation. Blackwater says its guards reacted lawfully to an attack on a U.S. convoy.
"The government will take the necessary legal measures against Blackwater depending on the investigation's results," Dabbagh said in a statement issued from New York, where Maliki will attend the U.N General Assembly. "The souls of Iraqis and their dignity are above everything else for us."
Soon after the shooting, Maliki had suggested the U.S. embassy stop using the North Carolina-based firm.
But U.S. Secretary of State Condoleezza Rice later promised a full review of how U.S. security details are conducted and Iraqi security officials have since echoed her words in saying private guards perform important work in Iraq.
Dabbagh said the joint committee investigating the incident had held its first meeting on Sunday. (Additional reporting by Aws Qusay in Baghdad)
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