Iraq's leaders presented the crackdown as a success so far in depriving the terror network of what has been its most prominent urban stronghold since it lost hold of cities in Iraq's western Anbar province.
But the flight of al Qaeda fighters raises the concern they can regroup elsewhere, as has often happened in the past.
Yassin Majid, an adviser to Prime Minister Nouri al-Maliki, said most of the leading insurgents had fled to the outskirts of Mosul or to a neighboring country amid the operations. He did not name the neighboring country. Mosul is about 60 miles from the Syrian and Turkish borders.
"Operations will continue and the Iraqi army will not leave Mosul until security and stability have been accomplished," he told The Associated Press in a telephone interview.
Maj. Gen. Mark P. Hertling, the top U.S. commander in northern Iraq, whose forces are working with the Iraqi troops in the operation, said he didn't believe significant numbers of militants had escaped. He said Iraqi forces have surrounded the city with a circle of berms and checkpoints controlling entry and exits.
But he said some al Qaeda leaders, who directed their Mosul followers from outside the city, may have stayed away from Mosul ahead of the sweep to avoid arrest, he told The Associated Press.
"It's been very successful," he said. "I think the combination of the arrests plus the uncovering of a number of weapons caches will reduce the number of attacks in Mosul."
But he warned insurgents could try to strike back in the coming days with suicide bombings in the city.
The sweep was launched Thursday, after five days of preparatory operations and arrests in the city. U.S.-backed Iraqi police and soldiers have been conducting raids on homes and have fanned out with checkpoints on city streets, though no clashes have been reported in the city, 225 miles northwest of Baghdad.
Interior Minister Jawad al-Bolani said 1,068 people have been detained over the past week, but 94 were cleared and have since been released. Hertling said those detained included several high- and mid-level al Qaeda figures, including leaders of cells that organized suicide car bombings and facilitators for foreign fighters entering the country.
The assault on the Sunni al Qaeda in Iraq group was launched in the wake of two other major crackdowns against Shiite militiamen in the southern city of Basra and the Baghdad district of Sadr City in the past two months. Those two sweeps continue but uneasy truces with the powerful Shiite Mahdi Army militia have eased the heavy violence they sparked.
Al-Maliki said Saturday the series of crackdowns would bring a boost to reconciliation efforts, saying it has "reflected positively on the political process."
Al-Bolani told a gathering of some 300 former Saddam Hussein-era officers in Mosul that the army and police would make room for them and that al-Maliki was urging them to return. Many in the crowd cheered the announcement.
Mosul's Sunni Arab population was once a major source of officers for Saddam's army, many of whom were removed because of their ties to his regime in a purge that followed the 2003 U.S. invasion. Their bitterness is believed to have fueled the Sunni-led insurgency.
On Friday, al-Maliki offered amnesty and cash to fighters in Mosul who surrender their weapons within the next 10 days. Al-Bolani said no one has surrendered any weapons yet and warned they had "no other choice" but to comply or face being targeted by security forces in the coming days.
Al-Maliki made a similar offer to Shiite militias in Basra during the sweep there, but few surrendered weapons.
Rep. Pelosi Visits To Promote Elections
The prime minister returned to Baghdad from Mosul - where he has been overseeing the crackdown - to meet with House Speaker Nancy Pelosi, who made a surprise visit to Iraq on Saturday.
She welcomed Iraq's progress in passing a budget as well as oil legislation, and a bill paving the way for the provincial elections in the fall that are expected to more equitably redistribute power among local officials.
"We're assured the elections will happen here, they will be transparent, they will be inclusive and they will take Iraq closer to the reconciliation we all want it to have," said Pelosi. She also met with Iraq's parliament speaker Mahmoud al-Mashhadani, U.S. Ambassador Ryan Crocker and Gen. David Petraeus, the top American commander in Iraq.
Pelosi, who also traveled to Iraq in January 2007 shortly after the Democrats assumed congressional control, has been a sharp critic of the Bush administration's conduct of the war and has pressed for the withdrawal of U.S. troops from the country this year.
She also has called for the Iraqi government to contribute more money to the reconstruction of the country.
President Bush's Iraq war funding request failed in the House on Thursday as anti-war Democrats and Republicans unhappy about added domestic funding formed an unlikely coalition to kill, for now, $163 billion to support U.S. troops overseas.
In Other Developments:
On Saturday, a female suicide bomber blew herself up near an office for a U.S.-allied Sunni group, then a suicide car bomber struck an Iraqi police patrol heading to the scene in the Diyala provincial capital of Baqouba, northeast of Baghdad.
Police said at least 15 people were wounded in the attacks, including two children.