BAGHDAD, Iraq (CNN) -- Iraq is sending troops for a "decisive" battle with al Qaeda in Iraq militants in Mosul -- one of the cities where the fighters remain strong -- Prime Minister Nuri al-Maliki said Friday.

Extra police and soldiers are being deployed to the northern city to strip al Qaeda in Iraq of its sanctuaries and "incubators" there, Iraqi Interior Ministry spokesman Maj. Gen. Abdul Karim Khalaf said.

Iraqi and U.S. forces have tackled the militants elsewhere in Iraq, but both admit it will be a hard fight in Mosul, the capital of Nineveh province hit by a massive blast Wednesday that killed 34 people.

Al-Maliki said the attack, which was followed the next day by the assassination of the province's police chief while inspecting the damage, drove him to order the crackdown.

"This heinous crime committed against our people and sons in Nineveh hurt us but also gave us a push to expedite the activation of the operations command," he said in Karbala.

Khalaf of the Interior Ministry told reporters about 3,000 police would be added to the Mosul force. He said it would be a "big job" but added: "Our intelligence has infiltrated al Qaeda [in Iraq]."

Mosul, one of Iraq's largest cities, remains a nagging problem for U.S. and Iraqi authorities. Watch U.S. troops at work in Mosul's "Wild West" »

The city has been a destination for insurgents crossing into Iraq from Syria. Nineveh is one of the four northern Iraqi provinces where U.S. and Iraqi forces are combining to try to root out insurgents in Operation Iron Harvest. The others are Diyala, Tameem and Salaheddin.

The actions of al Qaeda in Iraq and their ability to attack are beginning to change because of the U.S. and Iraqi security forces, U.S. Army Maj. Gen. Mark Hertling, commander of Multinational Division North, told reporters earlier this week.

"I think a year ago we were often reacting to al Qaeda and what they were going to do next," he said on Tuesday.

"Now I think the tables have turned a little bit, and they are attempting to react [to] where we're going to go next, and that's a critical difference."

Hertling said that "we still have a very tough fight to go" in Mosul. But he added that there were growing numbers of capable Iraqi soldiers in the north that would help to prevent al Qaeda in Iraq regaining footholds once troops sent in to shut them down had moved on to other areas.

Meanwhile, the U.S. military announced Friday that coalition troops killed one person and detained 19 others in northern and central Iraq in raids targeting al Qaeda in Iraq. Five of the arrests were in Mosul.

Troops there seized two wanted individuals allegedly involved in the Ansar al Sunna insurgent group and three suspects thought to be senior terrorist leaders who have links to other militants in the region.

"We will continue to pursue al Qaeda in Iraq and other extremists wherever they take sanctuary," said Maj. Winfield Danielson, spokesman for Multi-National Forces-Iraq, the formal name for the U.S.-led forces.

Also Friday, Iraqi authorities gave new details about fighting a week ago involving a Shiite messianic cult in the southern cities of Basra and Nasiriya, saying that 53 people died and more than 100 were wounded.

They also announced a ban on the Ansar al-Mehdi movement suspected of starting the clashes and gave a warning to it and other such groups.

Authorities said the fighting began when cult members attacked Shiite pilgrims during the observance of Ashura, a four-day commemoration of an early Shiite martyr, a grandson of Mohammed. Security forces then squared off with the cult members.

The Interior Ministry's Khalaf said 30 cult members and seven security forces were killed in Basra, while six cult members and 10 security forces died in Nasiriya.

In Basra, 40 cult members and 22 security forces were wounded, while nine cult members and 47 forces were wounded in Nasiriya.

There were 172 people detained in Basra and 206 in Nasiriya. E-mail to a friend

CNN's Jomana Karadsheh contributed to this report.

All About Iraq • Al Qaeda in Iraq