Baghdad - At least 700 people were killed and 2,000 others wounded in Iraq in April, marking one of the deadliest months in the country, medical and security sources and witnesses said.

Sources told Deutsche Presse-Agentur dpa that the peak of violence in Iraq was in Baghdad's Sadr City, in which clashes have been ongoing between Iraqi forces and members of the Mahdi Army, loyal to radical Shiite cleric Moqtada al-Sadr, since March 25.

Fighting in Sadr City - a slum inhabited by 2.5 million people - killed some 450 people, most of them women and children, sources said.

In the northern city of Kirkuk, twin explosions killed 100 people and wounded 150, as dozens of bodies were found across the city.

Besides explosions and ongoing clashes, violence flared in the southern city of Najaf when militants gunned down al-Sadr's brother- in-law, Riyad al-Nuri.

Also in the south, the Iraqi government continued in April its security operation, launched in March, against the Mahdi Army and illegal militant groups in Iraq's second largest Shiite city of Basra.

Since the launch of the operation, hundreds of people have been killed, including US soldiers and Iraqi security forces.

In other news, a US soldier was killed on Wednesday in the province of Nineveh when a bomb targeted a US patrol, the US military said on Thursday.

The death brings the number of killed US soldiers to 4,063 since the US-led invasion of Iraq.

In April alone, at least 51 soldiers were killed, marking the highest death toll since September. (dpa)