Iraqi forces have broken through to the jihadist-besieged town of Amirli, where thousands of people have been trapped for more than two months with dwindling food and water.

"Our forces entered Amirli and broke the siege," security spokesman Lieutenant General Qassem Atta said.

Talib al-Bayati, an official responsible for a nearby area, also said that the siege of the Turkmen Shi'ite-majority town has been broken, as did Nihad al-Bayati, who had been fighting to defend the town against the jihadists.

Iraqi security forces, Shi'ite militiamen and Kurdish peshmerga fighters all took part in the operation, the biggest military success for Baghdad since a lightning jihadist-led offensive overran large parts of the country in June, sweeping security forces aside.

Iraqi forces later managed to stem the militant onslaught, but had since struggled to regain ground.

Residents of Amirli faced major shortages of food and water, and were in danger both because of their Shi'ite faith, which jihadists consider heresy, and their resistance to the militants, which has drawn harsh retribution elsewhere.