BAGHDAD - Security forces battled armed gangs and insurgents in two Iraqi cities today as bomb attacks killed 21 in the capital, highlighting the precarious task facing US-led forces trying to stem sectarian violence.
British troops and a column of armored personnel carriers rushed to Basra as armed gangs fought with Iraqi forces for more than an hour in the mainly Shi'ite city, where Prime Minister Nuri al-Maliki declared a state of emergency in June.
Police killed six insurgents in Mosul, a religiously divided city 390 km north of Baghdad and the scene of considerable recent violence, including a suicide attack on a Kurdish political party on Tuesday in which nine died.
US officers have warned that Iraq could descend into civil war unless violence was curbed. Last week, Washington poured thousands more US troops in Baghdad to calm the capital.
Washington says Baghdad is key to stability in the entire country and stressed it was keeping faith with Maliki.
"(President George W Bush) is impressed not only by his determination to get the job done, but the fact is that he is working aggressively to do these things," said White House spokesman Tony Snow in Washington.
The new Shi'ite-led government has promised to reconcile Iraq's rival sects but almost three months after Maliki took power, the bloodshed continues.
Simultaneous car bombs killed 13 and injured 43 in a busy commercial area of central Baghdad, police said.
Earlier on Wednesday, a roadside bomb in a small flea market in east Baghdad killed eight and wounded up to 28.
"The bomb exploded beside those people who were just here to earn their living. They were just selling junk," said Mohamed Karin, standing amid the scattered debris of old televisions and household utensils.
"An old man with his two kids were killed. What did they do? They were innocent," he said.
Fighting in Basra began with an attack on the office of the governor and governing council. Basra Governor Mohamed Alwaili said they were mainly from the powerful Bani-Asad tribe and police sources said they were avenging the killing of a leader.
"There were men from this tribe and others from Basra. They started shooting at the governor's building. We will stand firm against those who carry weapons," he said.
Aqil al-Furaiji, a member of the Shi'ite-led governing council, said one policeman was killed and five wounded. Television pictures showed Iraqi forces exchanging heavy fire while two British armored personnel carriers passed.
The British military said up to 180 British soldiers and 16 Warrior armored personnel carriers had been dispatched to back up Iraqi troops and police on the ground.
Major Charlie Burbridge said that British forces exchanged several minutes of fire with some of the armed fighters as they departed Basra, but no soldiers were wounded.
Wednesday's fighting followed violence in the normally quiet southern shrine town of Kerbala on Tuesday between the Iraqi Army and followers of a radical Shi'ite cleric.
The Iraqi Defence Ministry said on Wednesday 12 people were killed in the incident, including two policemen.
Kerbala police deployed more than 10,000 troops and officers in a security cordon around the city to stop several thousand followers of the cleric, Mahmoud al-Hasani, from returning after a march in the nearby town of Hilla.