Related reading:

FALLUJAH, Iraq, June 8 (Xinhua) -- Iraqi security forces on Wednesday pushed farther into the besieged city of Fallujah and seized part of a district in the city after fierce clashes with Islamic State (IS) militants, a military statement and a security source said.

"The counterterrorism forces have recaptured al-Shuhada district in south of Fallujah and raised the Iraqi flag over some buildings, as the troops' advance is continuing in the district," the statement said without elaboration.

A security source told Xinhua that the troops made a new progress in the morning when dozens of Humvees and armored vehicles entered part of al-Shuhada district in southern Fallujah, some 50 km west of the Iraqi capital of Baghdad, amid fierce clashes with IS militants and air strikes of U.S.-led coalition aircraft.

The troops raised the Iraqi flags on some houses scattered on southern part of the district while artillery, mortar rounds and rockets were pounding deep into the district to clear the way for the troops to achieve further advance, the source said on condition of anonymity.

The latest advance came four days after the troops made another progress when they pushed into the adjacent district of al-Nuaimia and captured part of it.

The troops' push into Fallujah was slowed down during the past few days by heavy resistance from IS inside the city, in addition to hundreds of hidden bombs are believed to be planted by the militants.

The security forces also wanted to avoid heavy casualties among tens of thousands of civilians who are reportedly trapped inside Fallujah.

Earlier, Brig. Gen. Yahya Rasoul, spokesman for the Joint Military Command, said that about 50,000 to 70,000 civilians are expected to remain in Fallujah.

Early in the month, the UN children fund warned that at least 20,000 Iraqi children remain trapped in the city of Fallujah where Iraqi security forces are fighting to drive out the extremist IS militants from the city.

Iraqi Prime Minister Haider al-Abadi announced on May 23 the launch of a major offensive to claim Fallujah and surrounding towns and areas.

Government troops and allied militias have currently been fighting for months to reclaim key cities and towns in Anbar from IS militants, who attempted to advance toward Baghdad after seizing most of Anbar province.

Iraq has been witnessing a wave of violence since the IS controlled parts of Iraq's northern and western regions in June 2014.