Iraq's prime minister said Wednesday his government was determined to crack down on private militias blamed for the country's spiralling sectarian violence, warning he would "strike hard" against any group that challenges state authority.

In a nationally televised news conference, Prime Minister Nouri al-Maliki also appealed to neighbouring states to cease meddling in Iraq's domestic affairs — an apparent reference to Iran and Syria, which are accused by the U.S. and Iraqi officials of aiding Sunni and Shia armed groups.

He blamed foreign fighters in groups such as al-Qaeda in Iraq and forces loyal to former President Saddam Hussein for driving violence that takes the lives of at least 40 Iraqis every day.

"I would like to state here that the root of the battle we are fighting in Iraq and the root of the bloody cycle that we are undergoing is the presence of terror organizations that have arrived in the country," al-Maliki said.

Al-Maliki has made similar commitments before to deal with the militias, but his most recent comments follow a news conference Tuesday by U.S. Ambassador Zalmay Khalilzad at which he said Iraqi leaders had agreed to set a timeline for achieving key political and security goals, including reining in such groups.

That task has been politically fraught for al-Maliki because his fragile Shia-dominated government derives much of its power from the Shiite political parties with powerful militias.

"We will strike hard at anyone who defies the law or transgresses on the authority of the state," al-Maliki said.