By Ahmed Rasheed and Khalid al-Ansary
BAGHDAD (Reuters) - The head of Iraq's biggest Sunni Muslim parliament bloc was killed at a mosque Friday, officials said, an assassination which could undermine efforts for sectarian reconciliation in Iraq.
Recently picked as leader of the Accordance Front, Harith al-Ubaidi was seen as a moderate able to broker peace among the bloc's groups and also with Shi'ites, Kurds and others who have struggled for power since the 2003 U.S. invasion.
An independent lawmaker and member of parliament's human rights committee, Ubaidi was also seen as a leading defender of the rights of Iraqi prisoners.
His killing comes as parties hold talks to form alliances ahead of a parliamentary poll due in January that is seen as a test of whether Iraq's feuding factions can live in peace after the sectarian bloodshed triggered by the war.
U.S. combat forces are due to leave Iraqi cities by the end of this month, and withdraw completely by 2012. Washington hopes political rapprochement can be reached before the troops depart.
The leader of Iraq's Shi'ite-led government, Prime Minister Nuri al-Maliki, ordered an investigation and condemned the killing, as did other leaders of Iraq's Shi'ite majority.
"This cowardly, repulsive murder is a failed attempt to plant sectarian strife and to strengthen the presence of the terrorist groups that have received fatal blows from our security forces," he said in a statement.
Ubaidi was leaving a mosque in west Baghdad after Friday prayers when he was killed.
"A man shot him with a pistol then threw a grenade at him inside the al-Shawaf mosque," said Saleem al-Jubouri, a spokesman for the Accordance Front.
"It could be al Qaeda behind this, or another armed group," he added, calling on the government to provide more security.
POLITICAL RAMIFICATIONS
Iraq's police and army have had success curbing violence in the past year, but deadly bombings and shootings remain common.
Police said six people died in the attack, including the assailant. They said the assassin, believed to be a teen-ager, shot Ubaidi twice in the head before opening fire on worshippers and throwing a grenade. He was then killed by mosque guards.
"Assassinations of political leaders have a huge effect on national peace, and these acts are meant to stoke renewed sectarian strife between Sunnis and Shi'ites, and also within feuding factions among the Sunnis," said Hazim al-Nuaimi, a political analyst at Baghdad University.
He predicted Ubaidi's death would cause splits within the Accordance Front, which has more than 30 seats in Iraq's 275 member parliament. Although small compared to Shi'ite and Kurdish blocs, the Front did well in this year's local polls.
Hashim al-Taie, a member of the bloc, dismissed predictions of divisions and said it was likely Abdul-Kareem al-Samarrai, who is also seen as a moderate, would lead.
"This incident will bring the bloc together ... I don't think it will have a negative effect on reconciliation because martyrdom bridges gaps between the blocs," he said.
Sunni Islamist groups such as al Qaeda regard moderate Sunni politicians as traitors, and have called for them to be killed.