Islamic State conflict: "Capturing Tikrit might be a prelude for the battle for Mosul"

The top US general has said "there is no doubt" Iraqi forces will drive Islamic State (IS) militants out of Tikrit, as the troops reportedly entered the city's northern areas.

Gen Martin Dempsey, chairman of the Joint Chiefs of Staff, was speaking at a hearing in the Senate in Washington.

Iraqi officials earlier said government troops and Shia militias held two-thirds of Tikrit's Qadisiya district.

But they have so far not made much progress in Tikrit's south and west.

The operation to retake the hometown of Saddam Hussein is the biggest offensive yet by the Iraqi government.

Iran is helping to co-ordinate the 30,000 soldiers and militiamen involved. But the operation is not being supported by US-led coalition air strikes.

IS captured Tikrit last June after the Iraqi army collapsed in the face of a lightning advance by the group across northern and western Iraq.

Bridge 'bombed'

"There's no doubt that the combination of the [Iranian-backed] Popular Mobilisation forces and the Iraqi security forces, they're going to run ISIL [IS] out of Tikrit," Gen Dempsey said.

Iran is helping to co-ordinate the operation, which is not backed by the US-led coalition

It is not clear how many soldiers and militiamen have been killed or wounded in the offensive

There have been concerns about the overt involvement of the Iranian military in the operation, with top Revolutionary Guards commander Gen Qasem Soleimani reportedly overseeing it.

Some analysts have also expressed fears that Shia militiamen fighting alongside government forces may carry out reprisals for the massacre by IS fighters and allied Sunni tribesmen of at least 700 soldiers, most of them Shia, at nearby Camp Speicher in June.

However, Gen Dempsey said: "The activities of the Iranians to support the Iraqi security forces is a positive thing in military terms against [IS]."

But he also added: "The question is what comes after, in terms of their willingness to let Sunni families move back into their neighbourhoods, whether they work to restore the basic services that are going to be necessary, or whether it results in atrocities and retribution."