Just two days after British troops pulled out of downtown Basra, Iraq's second-largest city and center of the country's oil-rich south, fighting erupted between rival Shiite groups in street battles Thursday.
An eyewitness reported that masked gunmen swept through the center of the city carrying AK-47s and rocket launchers as members of Moqtada al Sadr's Mahdi Army and the Fadhila Party, which controls the province, apparently fought over a government building just vacated by British troops.
The turmoil in the capital of the southern province, home to a key port and most of the country's oil wealth, signals the beginning of the kind of battles that could erupt in Iraq as outside forces depart, say analysts. "There will be a power vacuum in Basra," says Martin Navias, an analyst at the Centre for Defence Studies at King's College in London. "As the British begin to extricate themselves from Basra, there will be fighting among these groups."
Fadhila officials said that "neighboring" countries, in a veiled reference to Iran, were backing certain factions in Basra including an individual they named who has known links to Mr. Sadr. "Iranian influence in southern Iraq is very strong and there are loads of Iranian personnel running around Basra, but which faction they are coming down for is unclear," says Mr. Navias.
"The British adopted a policy of live and let live. They never confronted the Shiite militias unless they were pushed in certain situations .... This allowed the different factions to assume power in the governing council, police and other institutions."
The Iraqi eyewitness to the fighting, who identified himself as Abu Ali, a Shiite contacted by phone in Basra, says, "It was unreal, some [of the fighters] looked like they were 12 years old." He didn't give his real name for fear the Mahdi Army will target him. "They were shouting: Moqtada, Moqtada."
He escaped the fighting on a side street and heard heavy gunfire and explosions. Shopkeepers began to close and run away too. "It was horrible. I barely escaped alive," he says.
Hassan al-Shimmari, the head of Fadhila, told the Al Arabiya news channel from Amman, Jordan, that the situation was so bad that the provincial governor had to use a weapon during the clash to help defend the governorate building and his home that is nearby.
"Our initial information indicates that there is a person who goes by the name Abu Qader, who leads these operations.... He is connected to a neighboring country. He received significant funds and weapons from this country to recruit fighters and undermine the security situation in the province of Basra," he said in reference to Iran, though he did not name it specifically.
Sources in Mr. Sadr's movement in Baghdad and Basra said that Abu Qader was in the Mahdi Army.
Reuters reported that hospital sources said seven people had been wounded in the clashes. Shortly after midday Thursday intense gunfire dwindled to sporadic shooting.
A curfew was imposed for several hours as Iraqi police, soldiers, and British troops deployed in the area.
"We don't have a great deal of clarity on what happened but police asked us to deploy our forces in that part of the city. By the time we got there there wasn't much to see," said British military spokesman Lieutenant-Colonel Kevin Stratford-Wright.
Details of the fighting were sketchy but Ali al-Hamadi, the head of Basra's emergency security committee, blamed it on a "misunderstanding" between Fadhila and the Mahdi Army.
Officials of Mr. Sadr's movement and the Fadhila Party sought to play down the violence. "Whatever is happening, there is no problem between us and the Sadrists. There is no way we would clash with them," said Nadim al-Jabiri, a senior official of Fadhila.
Salaam al-Maliki, a Sadrist and former transport minister, blamed the fighting on a personal dispute between the director general of the electricity directorate and an engineer.
"The picture is not clear. It seems the engineer has brought members of his tribe. It is a tribal thing, not political."
British Prime Minister Tony Blair said in February that Britain would begin withdrawing a quarter of its 7,000 troops stationed mainly in and around Basra.
While Basra has not experienced the levels of violence seen in the capital Baghdad, criminal gangs have taken root amid fighting between rival Shiite militias and political parties for control of its vast oil wealth.
Basra, whose oil accounts for almost all of Iraq's state revenues since northern export pipelines have been crippled by bombings, is a major prize for all parties.
Meanwhile, in Baghdad, UN Secretary-General Ban Ki-moon was left shaken but unhurt Thursday on his first visit to the capital after a Katyusha rocket landed just meters from a building where he was giving a news conference.
Moments after telling journalists he might boost the UN's presence in Iraq because of improved security, a thunderous blast sent shockwaves through the conference venue, startling Ban and sending him ducking for cover behind a podium. Security guards grabbed Iraqi Prime Minister Nouri al-Maliki who was standing next to Ban at the time and was dusted by small bits of debris that fell from the ceiling.
• Material from Reuters was used in this report.