Mortar shells barraged a Shiite enclave north of Baghdad, killing at least three people on Saturday, police said, while officials in Kirkuk warned that a string of deadly bombings showed that insurgents were finding new ways to thwart strict security measures.

About 16 mortar shells rained on houses in the Sharqiya residential area in Khalis, 50 miles north of Baghdad, police said. They said 24 people were wounded in addition to the three killed.

Khalis is a mainly Shiite area in the volatile Diyala province and is frequently targeted by suspected Sunni insurgents.

Farther north, storekeepers in Kirkuk swept broken glass and other debris from the bloodstained pavement hours after a series of bombs struck commercial areas in the disputed city, killing at least four people and wounding 38.

The attacks started Friday evening when a bomb struck a mainlyTurkomen open-air market in the Qoriyah district in the city center, killing two people and wounding 25, police Col. Burhan Tayeb Taha said.

Three more explosions struck the city within three hours, killing two people and wounding 13, Taha said.

Police said at least three women and five children were wounded, including 4-year-old Diyar Mohammed.

"I was there to buy a toy for him and he was injured when shrapnel hit his head," his mother Narmeen Salih said as she sat beside him in the hospital.

The apparently coordinated attacks came four days after a quadruple suicide truck bombing that killed hundreds of members of the minority religious Yazidi sect in northwestern Iraq.

Minority sects such as the Yazidis and Turkomen are especially vulnerable as militants seek new targets to avoid a U.S.-Iraqi military crackdown on Baghdad and surrounding areas to stop violence among warring Sunni and Shiite factions.

The U.S. commander overseeing the cleanup in the northwestern villages that were devastated by Tuesday's attack said Al-Qaeda in Iraq fighters were taking aim at remote communities after being chased out of the larger cities such as Mosul and Tal Afar.

"They're moving out of the cities into these hamlets and villages in order to establish safe havens," said Col. Stephen Twitty, commander of the 4th Brigade Combat Team in Mosul, another northern city to the west of Kirkuk. "We have targeted many of these villages, but ... it's like a needle in a haystack."

"You can easily build a car bomb in someone's garage, in someone's village somewhere and those are the things that we have to continue to just put pressure on," he told AP Radio.

Authorities in Kirkuk, 180 miles north of Baghdad, said the main street had been closed to vehicles to prevent the threat of car bombs. But Maj. Gen. Jamal Tahir, the general-director of police in Kirkuk, said the explosives that struck Friday were apparently wrapped in plastic bags and hidden in the garbage, and he appealed to civilians to be alert and report anything suspicious.

"The terrorists are changing their tactics in carrying out their crimes, so police and civilians should be more aware and open-minded to ensure security," he said. "I will not say that we will put a policeman at each garbage site or any other place, but I want to say that civilians should cooperate with security personnel in preventing terrorists from committing their crimes."

The U.S. military also has warned that militants will try to step up attacks this month in a bid to upstage a pivotal progress report on Iraq due to be delivered in September by the top commander Gen. David Petraeus and U.S. Ambassador Ryan Crocker.

Prime Minister Nouri al-Maliki, trying to shore up his crumbling government, and President Jalal Talabani addressed a conference of Iraqi diplomats in Baghdad, stressing the need for friendly relations and support from all neighboring countries.

The Shiite-led government has been accused of bias toward Iran and against mainly Sunni Arab countries in the region, as well as threats of a Turkish incursion to face separatist Kurdish rebels in northern Iraq. "Iraq has exerted and is still exerting great efforts to form the best relations with the Arab countries," Talabani said. "We do not want to face the countries that are hostile to us, but we cannot sit silent forever. If things are not solved in a friendly way, Iraq is not as weak as they think."

Al-Maliki has made a series of speeches in recent days as he tries to save his paralyzed government from collapse, even traveling on Friday to Saddam Hussein's hometown of Tikrit, where he told Sunni tribal chieftains that all Iraqis must join to crush al-Qaida in Iraq and extremist Shiite militias "to save our coming generations."

And on Thursday, the prime minister signed a political manifesto, creating a new alliance with the Shiite Supreme Islamic Iraqi Council and the country's two main Kurdish political parties.

The dramatic new overtures illuminate al-Maliki's fear of a quick U.S. troop withdrawal and his desperation to show progress on political reconciliation before the progress report to be delivered to Congress next month.