Iraqi forces are advancing into the centre of Ramadi in an attempt to drive Islamic State(IS) militants from the city.
US-backed Iraqi troops had retaken two districts and entered two others before advancing to the main government complex of Ramadi, after IS took hold of the city in May.
Iraqi counter-terrorism service spokesperson Sabah al-Numani told the BBC its troops have begun the assault on the centre of the city.
He says troops, along with soldiers, police and Sunni tribesmen are purging residential areas and "the city will be cleared in the coming 72 hours".
Temporary bridges built over the River Euphrates, which flows along the north and west of the city centre allowed troops to enter directly southwest of the government complex, sources told the BBC.
If Iraqi troops recapture Ramadi, it will be the second largest city to be taken back from IS in the past 18 months, boosting morale of the Iraqi security forces and Sunnis opposing IS in Iraq.