Iraqi forces have hailed progress in the military operation to retake the city of Ramadi from Islamic State.
Officials said they have made the most significant incursion into the city, west of Baghdad, since it fell to the hands of the militants in May.
Losing Ramadi - the capital of the sprawling western Anbar province and Iraq's Sunni heartland - was a major blow to the Iraqi government in May this year. It was also the biggest defeat since IS militants swept through areas in the country's north and west, including Iraq's second-largest city of Mosul in the summer of 2014.
Iraqi forces announced a counter-offensive shortly after Mosul fell but progress has been sluggish and clawing territory back from IS has proven more difficult than expected.
But on Tuesday, Iraqi spokesman Sabah al-Numan said the troops crossed the Euphrates River north of the city and its Warar tributary to the west and pushed into central Ramadi.
Sporadic clashes are under way and Iraqi forces are being forced to remove roadside bombs the IS extremists had planted as they push forward, Mr al-Numan added.
He said no paramilitary forces - a reference to pro-government Shiite militias whose actions have raised concerns in Sunni territory - are taking part in the operation. The Iraqi air force and the international coalition are providing air support to troops on the ground and bombing IS targets.
Since over-running Ramadi, Islamic State has destroyed all the bridges around the city. It also demolished the Anbar operations command and fanned out into the city's residential areas to set up less conspicuous centres of command.
As the operation to retake the provincial capital progresses, Ramadi's sizeable civilian population - estimated to be between 4,000 and 10,000 - remains mostly trapped inside the city. Iraqi officials say they believe civilians will be able to flee the city, but coalition officials report that so far they have only witnessed small groups do so.