Up to 310 civilians, including 60 children, were killed and at least 1,257 wounded in documented attacks on 35 bakeries during 2012, the Syrian Network for Human Rights said in a statement Tuesday.
The attacks as people stood in line for bread are "no clearer and definitive evidence of the deliberate targeting" of civilians by the Syrian regime, SNHR said.
The number of documented attacks, the group said, "indicates that it's a widespread crime and the increasing number proves that it's systematic."
Some of the bakeries were targeted multiple times, the statement said.
In one instance, SNHR said, Syrian tanks "bumped" hundreds of people standing in a long queue at the al-Zora bakery in Hananu in October, killing 20 people and injured more than 45.
Violence from the nearly 2-year conflict spilled over into Iraq Monday when at least 40 Syrian soldiers and several Iraqi troops were killed in an ambush, The New York Times reported.
Iraqi officials said the group was ambushed in Anbar province by unidentified gunmen as Iraqi troops were escorting the Syrian forces back to Syria in a bus convoy.
At least seven Iraqis were killed in the attack, the first such killing of Syrians in neighboring Iraq since the Syrian uprising began two years ago this month.
Ali al-Musawi, a spokesman for Prime Minister Nouri al-Maliki, accused "armed groups from the Iraqi and Syrian side" of coordinating the attack. He said Iraq would station more security forces along its border with Syria.
Al-Musawi did not say which armed groups he considered responsible for the attack, but The New York Times said it was evident he meant Sunni militant extremists aligned with al-Qaida in Iraq. Maliki is a Shiite who critics accuse of trying to marginalize Iraq's Sunni population now that U.S. troops are gone.
In Turkey, officials said Syria fired as many as 90 Scud-type missiles into residential areas in the last two months, the Hurriyet Daily News reported
Syria's military separately launched a new offensive on the western-central cities of Homs and Hama. Anti-Assad activists reported heavy fighting between rebels and regime forces backed by tanks and warplanes.
The number of refugees who fled Syria to escape the violence in the nearly 2-year old battle between government forces and those opposed to President Bashar Assad is expected to exceed 1 million this week, U.N. officials said.
As of Sunday, the total number of registered refugees and individuals awaiting registration is 975,337, U.N. statistics released by the organization's refugee agency indicated. The data included 8,262 Syrian refugees registered in North Africa.
UNICEF, the U.N.'s children's agency, reported 20 percent of schools in Syria have been damaged or destroyed since the conflict began.
In its latest assessment, UNICEF said at least 2,400 schools have been damaged or destroyed, including 772 in Idlib province, and 300 each in Aleppo and Deraa.
In some of the worst areas, many children have missed nearly two years of schooling, UNICEF said.
A group of opposition officials announced formation of an elected provincial council in Aleppo, a move endorsed by opposition leader Moaz al-Khatib, The Washington Post reported.
However, dissident blogger Ammar Abdulhamid said the announcement came from Turkey, indicating how far rebels had to go to establish normal governance in Aleppo.