BAGHDAD (AFP) - At least 26 people were killed in a string of attacks in Iraq on Wednesday, including a dozen people who lost their lives in a rush-hour bombing in Baghdad and two US troops slain by an Iraqi comrade. In the deadliest single attack of the day, a booby-trapped car exploded, followed by another bomb blast at a bus station in the working class district of Baghdad al-Jadida in the east of the capital, killing 12 people and wounding 60 others, an Interior Ministry official said. In the northern city of Mosul, an Iraqi soldier on joint patrol with US troops opened fire on his American comrades, killing two of them, the Ministry said. A Ministry source said a US soldier "slapped an Iraqi soldier during the patrol and he opened fire in response." US military spokeswoman Major Margaret Kageleiry said of the incident: "Two US soldiers have been killed today (Wednesday) in Mosul. I can't make further comment." In Mosul, the intruders killed sisters Lamia and Walaa Sabih and wounded their mother before booby-trapping the house. When police arrived a bomb went off, wounding two of them, an officer said on condition of anonymity. The US military said in a statement that five bombs were placed in the home and two exploded. The two women - one of whom was the mother of three children - both worked for the provincial council, which released a statement condemning the attack. Another 10 people were killed in a string of bombings in Baghdad, which has seen near-daily attacks in recent days despite an overall improvement in security over the past year. Iraq's Prime Minister Nuri al-Maliki stepped up a war of words with the country's Kurdish parties on Wednesday over pro-government armed groups that could undermine the parties' power. Maliki expressed his "deep regret at the media escalation" over the so-called Support Councils, local tribal groups across Iraq who have allied with the government to help improve security in the war-torn country. "It was necessary to form the Support Councils to preserve law and order in the provinces that had seen a breakdown in security," Maliki said in a statement. The Kurdish parties have criticised the formation of the councils in mostly Kurdish areas, accusing Maliki of creating illegal proxies aimed at foiling their aspirations for a greater autonomous Kurdish region. The councils "were greatly welcomed by all the parties and powers, including the two Kurdish parties," Maliki said. "But this turned into opposition when, regrettably, some parties and some selfish people saw that the support councils started to threaten their projects when they conflicted with the higher national interest."