The New Nation - Internet Edition

AP, Baghdad

At least 25 including four US troops were killed in a string of attacks across Iraq on Wednesday.

At least 23 people were killed in a string of attacks across Iraq on Wednesday, including a dozen people who lost their lives in a rush hour bombing in Baghdad and 4 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 a working class district of Baghdad, killing 12 people and wounding 60, according to the interior ministry.

In the chaotic northern city of Mosul, an Iraqi soldier opened fire on his American comrades, killing 4 and wounding another six, according to the US military and the Iraqi ministry of defence.

A security source told DPA that the "Iraqi soldier opened fire on a group of US soldiers after an angry dispute. The Iraqi soldier died in the fire exchange."

BAGHDAD (Reuters) - An Iraqi soldier went on the rampage at a joint security station in northern Iraq on Wednesday, shooting dead two U.S. soldiers and wounding six, the U.S. military said.

The U.S. military said the soldier opened fire on the Americans at the station-one of many in which Iraqi and U.S. troops operate side by side-in the city of Mosul.

"The soldiers were in the courtyard t an Iraqi soldier entered and shot two soldiers, killing one, mortally wounding another, and then spraying the others," said U.S. army spokeswoman for northern Iraq Major Peggy Kageleiry.

"He was engaged by counter-fire and killed," she added. A local morgue said it had received the body of the Iraqi soldier, riddled with bullets.

Two local police sources and an Iraqi army source, all of whom declined to be named because of the sensitivity of the subject, said a quarrel had broken out between the Iraqi and U.S. soldiers at the joint station.

But Kageleiry denied there was any altercation between the soldiers before the shooting.

"The U.S. soldiers had no conversation with this soldier and there was no interaction of any kind before they were murdered," she said.

Elsewhere in Mosul-which the US military call one of the last bastions of Al-Qaeda in Iraq-two Christian sisters were slain by gunmen who broke into their home and wired it with bombs.

The intruders killed 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 that two exploded.

The women-one the mother of three children-both worked for the provincial council, which condemned the attack.

More than 2,000 Christian families fled Mosul in October after a wave of killings there.

The United Nations High Commissioner for Refugees (UNHCR) said on Tuesday that some Christians were starting to return, with around a third of the families in one neighbourhood coming back to their homes.

After the latest killings the governor of the Nineveh province, where Mosul is the capital, transferred the head of security for the province to Baghdad and appointed a replacement, a senior military official said.

The order "came after Nineveh witnessed violent operations, especially during the last month, including the dispersal and targeting of hundreds of Christian families," the official said, adding that Baghdad had been forced to send another two brigades to Mosul.

More than 200 Iraqi Christians have been killed across Iraq since the 2003 invasion and a string of churches have been attacked, with the violence intensifying in recent months, particularly in the north.