The "Islamic state" organization has seized the city on 17 of current month.

But he said more support was needed from international coalition partners.

Iraqi forces have suffered a number of defeats at the hands of IS over the past year, and fled from a smaller militant force in Ramadi last week.

On Sunday, US Defence Secretary Ashton Carter said that the rout showed Iraqi troops lacked the will to fight.

Mr Carter told CNN that the Iraqis had chosen to withdraw despite the fact that they "vastly outnumbered" IS forces.

'Small nuclear bomb'

In a BBC interview, Mr Abadi said he was surprised at the US defence secretary's comments.

"[Mr Carter] was very supportive of Iraq and I am sure he was fed with the wrong information," he said.

The prime minister added that his forces were fazed by IS shock tactics.

"They have the will to fight but when they are faced with an onslaught by [IS] from nowhere... with armoured trucks packed with explosives, the effect of them is like a small nuclear bomb - it gives a very very bad effect on our forces," he said.

"It makes my heart bleed because we lost Ramadi, but I can assure you we can bring it back soon," he said.

Ramadi and its surrounding area has seen fierce fighting since January 2014 when IS fighters took control of the nearby city of Fallujah.

Prime Minister Abadi said Iraq needed more international support as many IS fighters were slipping into Iraq from Syria and bringing new tactics to the fight.

"Not controlling Syria-Iraq border more closely was an error. Syria is in chaos which made IS become stronger. We've asked our international coalition partners to tighten control over the border," he said.

Mr Carter said the situation in Ramadi was "very concerning".

"We can give them training, we can give them equipment - we obviously can't give them the will to fight."

Ramadi is just 110km (70 miles) west of Baghdad.

Mr Abadi said that dealing with the displaced was a "genuine humanitarian problem" but that he hoped that they would return home as soon as Ramadi was liberated.

Anbar province, which is predominantly Sunni, covers a vast stretch of the country west from Baghdad to the Syrian border, and contains key roads that link Iraq to both Syria and Jordan.

In addition to Ramadi, IS militants have also seized the last Syrian government-controlled border crossing with Iraq.

The Iraqi Prime Minister confirmed that Ramadi will be retaken in days.

He said that his government , army volunteers are supporters to his "plan" to achieve this goal, pointing to "the emergence of signs that they are succeeding."