BAGHDAD -- Thousands of Iraqi troops launched a crackdown in Kirkuk yesterday, ordering residents to stay in their homes in an effort to put down violence that has swelled in the north amid efforts to rein in bloodshed in Baghdad.
Elsewhere in the north in the town of Tal Afar, a suicide bomber rammed a police checkpoint with a car packed with explosives, killing four policemen and 10 civilians. Some of them died when parts of nearby homes collapsed from the force of the blast . It was the deadliest attack in a day that saw 26 Iraqis killed around the country.
In March, President Bush had pointed to Tal Afar as an example of progress made in bringing security to Iraq after a major US offensive swept through the town, 30 miles from the Syrian border.
But after a period of quiet, yesterday's was the fourth suicide attack in the town in the past three weeks.
Thousands of US and Iraqi troops have been carrying out an intensified sweep of Baghdad since August, searching neighborhoods to root out insurgents and militias who have killed thousands this year.
But at the same time, shootings, bombings, and other attacks have been more frequent in northern areas such as Kirkuk and Mosul, the capital of the province where Tal Afar is located -- though the bloodshed has not been on the scale seen in Baghdad.
The US military announced yesterday that a US soldier was killed Friday near Beiji, about 60 miles southwest of Kirkuk.
Authorities in Kirkuk, 180 miles north of Baghdad, last week completed digging a 10-mile trench around the city's southern and western edges aimed at cutting off side roads to prevent car bombs from being brought into the city. Intensified checkpoints were set up on the city entrances.
Authorities yesterday announced that a curfew ordering all residents off the streets had been expanded to around-the-clock ``until further notice," said Kirkuk police chief Lieutenant General Sherko Shaker.
``This operation comes as a measure to cleansing Kirkuk from weapons, as well to prevent the militants from having any chance to reorganize their abilities," he said. ``We shouldn't give them any chance to rest."
Troops conducted searches and raids yesterday in the southern and western sectors of the city, where most of the Sunni Arab population is located. So far, 150 suspected Sunni insurgents have been arrested and more than 220 assault rifles have been seized, Shaker said.
Kirkuk is a major oil center and the focus of an ongoing struggle for power between its large Sunni and Kurdish populations.