The local official in Iraq's Salaheddin province said allied Iraqi forces entered Tikrit through its northern Qadisiyya neighborhood. He spoke on condition of anonymity as he was not authorized to brief journalists.
Video obtained by The Associated Press showed troops and militiamen marching alongside Humvees flying Iraqi military and Shiite militia flags in that northern neighborhood.
Tikrit, the capital of Salahuddin province, lies about 130 kilometers north of Baghdad. It is one of the largest cities held by Islamic State militants and lies on the road connecting Baghdad to Mosul. Retaking it will give Iraqi forces a major supply link to retake Mosul.
Iraqi forces retook the town of Alam, which borders Tikrit, yesterday, sealing off Tikrit to prepare for an offensive inside the city. Hidden bombs and snipers had slowed the troops' progress.
Iranian military advisers have been helping guide Iraqi forces in their advance on Tikrit. Among those directing operations is Iranian Gen. Qassem Soleimani, commander of the powerful Revolutionary Guard's Quds Force.
The US says its allied coalition carrying out airstrikes targeting the extremists has not been involved in the Tikrit offensive.
The Islamic State group holds about a third of Iraq and neighboring Syria in its self-declared caliphate.
