Bombers killed 12 people in northern Iraqi towns and villages on Monday in the second consecutive day of attacks in areas at the center of a bitter feud between Baghdad and autonomous Kurdistan.
The ethnically mixed, disputed territories - the swathe of land marking Iraq from the area administered by Kurds in the north - have been a potential flashpoint for conflict since the buffer of the last American troops left a year ago.
Two blasts hit a Shi'ite district in Tuz Khurmato, killing at least five and wounding 24 and a truck bomb killed seven in a Shabak minority area near Mosul, 390 km (240 miles) north of the capital, security and local officials said.
"The bombers are trying to stir tensions, but we are telling them we will be more unified by these attacks," Tuz Khurmato Mayor Shalal Abdul told Reuters. "Those who were killed here include three children and an elderly man."
No group claimed responsibility for Monday's attacks, but the explosions came at a time of heightened tensions between the Arab-led central government in Baghdad and ethnic Kurds over contested land and oil rights.
One person was killed and five were wounded in four blasts around the religiously mixed city of Baquba in Diyala province, where some areas neighboring Kurdistan are disputed, police said.
Last month, Baghdad and Kurdistan sent troops and tanks from their respective armies to reinforce positions around towns in the contested territories, escalating tensions in their long-running dispute, especially over Kirkuk.
Neither Iraqi Prime Minister Nuri al-Maliki nor Kurdistan President Masoud Barzani stand to benefit from letting the standoff slide into conflict, but they may try to use troop movements to shore up support with their constituents, diplomats and analysts say.
Iraqi troops and Kurdish Peshmerga forces have faced off in the past only to step back before any major confrontation. U.S. officials helped ease tensions earlier this year when the two armies faced off near the Syrian border.
Another 11 people were killed in attacks in the ethnically mixed city of Kirkuk on Sunday, authorities said.
Kirkuk sits outside the three northern provinces administered by Kurdistan, but ethnic Kurds lay historical claim to the city and say it should be part of the Kurdish region. The city's Turkmen minority also claim historical rights there.
A referendum to decide if Kurds are the dominant ethnicity, which would strengthen their claim to Kirkuk and its oil riches, has been repeatedly delayed.
Kurds say Iraq's former Sunni dictator Saddam Hussein "Arabised" Kirkuk by moving Arabs there in the 1980s and 1990s.
Kurdistan has run its own government and armed forces since 1991 and is more secure and stable than other parts of Iraq, but it still relies on the central government for a 17-percent share of the national budget and for pipelines to export its oil.
But the Kurdish region increasingly has clashed with Baghdad after signing oil agreements with companies like Exxon Mobil and Chevron to develop its own oilfields, deals the central government dismisses as unconstitutional.