Iraq's minister of water resources has played down warnings that Mosul dam will collapse, estimating only a "one in a thousand" chance of failure and saying the solution was to build a new dam or install a deep concrete support wall.

The US military has warned that a collapse of the 3.6 km-long (2.2 mile) hydroelectric dam located near Islamic State-held territory in the country's north would be catastrophic.

An Italian company has been awarded a contract to make urgent repairs to the dam which has suffered from structural flaws since its construction in the 1980s and requires constant grouting to maintain structural integrity.

"The looming danger to Mosul dam is one in a thousand. This risk level is present in all the world's dams", Muhsin al-Shammari said in an interview to al-Sumaria TV.

He said one solution was to build a concrete support wall 150 to 200 meters deep. In the meantime, workers are removing 5 to 6 tonnes of concrete a day at a cost of 7 billion Iraqi dinars ($6 million) a day, he added.

Islamic State militants controlling swathes of territory in northern and western Iraq seized Mosul dam in August 2014, raising fears they might blow it up and unleash a wall of water on Mosul and Baghdad that could kill hundreds of thousands along the heavily populated Tigris River valley.

Kurdish Peshmerga fighters recaptured the dam two weeks later with the help of coalition airstrikes and Iraqi government forces.

About 450 Italian forces will be deployed to protect the Italian Trevi Group contracted to repair the dam, whose deterioration has forced the US military to draft a contingency plan for its potential failure. – Reuters