(Adds Interior Ministry spokesman)
By Aws Qusay and Wisam Mohammed
BAGHDAD, Jan 25 Iraqi security forces have begun a "decisive" final offensive against al Qaeda in Iraq to push the Sunni Islamist militants out of their last major stronghold in the north, Prime Minister Nuri al-Maliki said on Friday.
He said Iraqi soldiers and police were being sent to Mosul, where a massive blast blamed on al Qaeda killed 40 people and wounded 220 on Wednesday, and an operations room had been set up in the city, 390 km (240 miles) north of Baghdad.
U.S. military commanders say al Qaeda, blamed for most big bombings in Iraq, has regrouped in the northern provinces after being squeezed out of western Anbar province and from around Baghdad during security crackdowns last year.
They describe Mosul, capital of Nineveh province, as al Qaeda's last major urban stronghold in Iraq.
"We have set up an operations room in Nineveh to complete the final battle with al Qaeda along with guerrillas and members of the previous regime," Maliki said, referring to other Sunni militants the Shi'ite-led government says remain loyal to former leader Saddam Hussein.
"Today our forces started moving to Mosul. What we are planning in Nineveh will be decisive," he said during a ceremony for victims of violence in the holy Shi'ite city of Kerbala in southern Iraq, broadcast on state television.
Maliki gave no details of the number of Iraqi troops involved or the scale of the operation. Defence Ministry spokesman Mohammed al-Askari did not have details but said it had been launched at Maliki's request.
"Security is very weak there and the security forces need to be reinforced," Askari said.
Iraqi Interior Ministry spokesman Major-General Abdul-Kareem Khalaf said the Mosul push would include 3,000 extra police. Iraqi security officials in the city said no reinforcements had arrived yet.
U.S. and Iraqi troops have launched a series of offensives in northern provinces this year targeting al Qaeda in Iraq.
The U.S. military calls the group, which commanders say is largely foreign-led, the biggest threat to Iraq's security. The military said this week that al Qaeda militants killed 3,870 civilians and wounded almost 18,000 in 4,500 attacks last year.
"We defeated al Qaeda, now there is just Nineveh province where they escaped to, and Kirkuk," Maliki said, referring to another northern city.
During his trip to Kerbala, Maliki met Sheikh Abdul Mehdi al-Karbalai, a representative of Iraq's top Shi'ite cleric Grand Ayatollah Ali al-Sistani. Karbalai was lightly wounded in a bomb attack in the city late on Thursday.
Maliki called the bombing a "criminal act".
U.S. military commanders say al Qaeda's influence in its former strongholds has been greatly diminished but that it remains a dangerous enemy in Mosul and other northern areas.
Despite frequent attacks in northern Iraq, overall violence has fallen sharply across the country, with the number of attacks down 60 percent since last June.
The fall in attacks has been credited to an extra 30,000 U.S. troops that became fully deployed last June, the growth of neighbourhood police units after Sunni Arab tribal sheikhs turned against al Qaeda and better Iraqi security forces.
"Now we have a real army. The days when the militants could do anything in front of our armed forces are gone," Maliki said.
U.S. commanders in northern Iraq said Wednesday's massive blast, which left a crater the size of a multi-storey building, was in an unoccupied building they said was used by al Qaeda to store weapons and tonnes of explosives.
On Thursday, the Nineveh province police director was killed by a suicide bomber as he toured the site of the original blast. (Writing by Paul Tait; editing by Matthew Tostevin)