Stoppage of crude exports to Baghdad over payment dispute raises fears of a Kurdish push for greater independence.
At least 13 people, including a mother and her three children, have been killed after twin bomb blasts and a shooting attack in Abu Garma, a village in the central Diyala province.
The attacker, armed with silenced weapons, is believed to have shot the victims in the early hours of Friday.
“Unknown gunmen broke into a house in the village of Abu Garma and killed a 45-year-old woman and her three children”, who were between 10 and 15-years-old, Lieutenant-Colonel Ahmed al-Karkhi, a police official involved in the investigation in Diyala, said.
He said the attack, occurring only hours after twin bombings in a cafe in the same village, might have had a sectarian motive, and could lead to further violence.
“It seems like a sectarian incident, and there is a risk that it might lead to more sectarian violence in the area,” Karkhi said.
The attacks in Diyala come a week after a wave of blasts killed dozens in Baghdad, Kirkuk and Samara.
The two cafe explosions, occurring within minutes of each other on Thursday night, killed at least nine people and wounded another 21 in Abu Garma, Iraqi officials said.
“Most of those killed in the two attacks [on Thursday] were Shia, and the family killed [on Friday] was Sunni,” Karkhi said.
The first attack was set off by a suicide car bomber outside the packed cafe, an interior ministry official and a local police officer said.
Another bomb exploded inside the cafe a few minutes later.
The tolls were confirmed by a medic at the Baquba General Hospital.
The officials spoke on condition of anonymity because they were not authorised to talk to the media.
Abu Garma, a small village of between 150 and 200 people, is situated north of Baquba, the capital of Diyala. Baquba lies about 60km northeast of the Iraqi capital, Baghdad.
Diyala, a fertile agricultural province, has long been one of the most volatile regions in Iraq, inhabited by a mix of
Sunnis, Shias and Kurds.