Iraqi special forces Tuesday said they were fighting deep inside Ramadi ahead of a major operation planned to recapture the western city from Islamic State jihadists.
The forces crossed the Euphrates river at a secured point and penetrated the city centre, heading for government buildings, Sabah al-Numan, spokesman for the Anti-Terrorism agency, said.
The reported action came as a military source said that a full-scale operation to recapture the city had been postponed until Wednesday pending the arrival of some 200 US special forces.
Ramadi, capital of the province of al-Anbar which stretches from Baghdad to the Syrian and Jordanian borders, fell to the militants in May, in a major blow to the government of Prime Minister Haider al-Abadi.
Iraqi officials have since then repeatedly announced its imminent recapture.
Government troops have surrounded the city but Islamic State typically rigs elaborate booby-trap defences in the urban areas it is defending.
There are also fears for the remaining civilian residents, with officials accusing the extremists of preventing them from leaving in order to use them as human shields.
Islamic State remains in control of much of Sunni Arab northern and western Iraq, despite a US-led air campaign launched in the aftermath of its lightning advances in mid-2014.