Iraqi forces and Shiite militiamen inch closer to Tikrit as fighting with Islamic State continues. (Reuters)

Iraqi forces and pro-government militias have routed Islamic State fighters in two key areas near the city of Tikrit, officials said Sunday, one week after embarking on an ambitious offensive to retake one of the militants’ key strongholds.

Officials hailed the advances as significant progress in the battle to recapture Tikrit. But troops remained stuck outside the city Sunday, underscoring the difficulty of taking on Islamic State militants entrenched in urban areas.

Local television channels aired footage Sunday of pro-government militias entering the village of Abu Ajeel, east of Tikrit. Officials said the militias, recruited by the government to assist in the fight against the Islamic State, also secured the area of Dawr. Images from Dawr, which is south of Tikrit, broadcast on television showed empty streets and dun-colored homes damaged by the fighting.

[View: The military assault on Tikrit in pictures]

Iraqi forces “have entered Abu Ajeel and reached the center of Dawr, but the operations are ongoing,” said Ahmed al-Karim, head of the provincial council in Salahuddin, where Tikrit is located.

“It will still take days to completely liberate” the areas, he said. “There is resistance from [the Islamic State], but it is not at the level we expected.”

On March 1, Iraq’s government announced the start of the offensive to reclaim Tikrit, which the Islamic State seized in the summer as part of a sweep across northern Iraq. Many of the city’s residents have fled. Tikrit was the home town of former strongman Saddam Hussein and is populated mostly by Sunni Arabs.

In Dawr, which was home to top Hussein lieutenant Izzat Ibrahim Douri, Iraqi forces found dozens of booby-trapped cars and improvised explosives left behind by the militants, a local official said. Some Hussein-era officials are part of the Islamic State.

The Islamic State “controlled the area for more than nine months,” Iraqi lawmaker Dheaa al-Douri said of Dawr. “So it will take time to defuse the bombs and allow civilians to return.”

[Read: The Islamic State’s atrocities]

The lawmaker denied reports Sunday that a pro-government militia had kidnapped civilians who had stayed behind in Dawr. He said troops had evacuated the civilians to the nearby government-controlled city of Samarra.

Militias dominated by Iraq’s majority Shiites have spearheaded the Tikrit offensive, raising concerns about revenge attacks against local Sunnis suspected of collaborating with the Islamic State.

The well-armed militias, nominally controlled by the government and backed by Iran, have eclipsed the poorly trained Iraqi security forces on the battlefield.

As many as 30,000 Iraqi troops and militia fighters are participating in the offensive, officials say.

In footage aired from Abu Ajeel on Sunday, gunmen from the powerful Asaib Ahl al-Haq militia were shown leading the battle. In Dawr, fighters with the militia Kitaeb Hezbollah raised their flag over a mosque.

Security forces said they would move east to the area of al-Alam, where the Islamic State is still in control, before advancing on Tikrit.

“We imagined we would do [the operation] in less time, but the enemy has planted bombs everywhere,” Qais al-Ghazali, the head of Asaib Ahl al-Haq, said in a televised news conference Saturday. “But we changed our tactics” and are moving forward, he said.

The government has not given any casualty figure.

Mustafa Salim contributed to this report.