There has been fierce fighting in Iraq's Anbar province, with reports that the Islamic State of Iraq and the Levant (ISIL) group has seized a strategic bridge that connects the cities of Baghdadi and Haditha.
Iraqi troops have been trying to recapture Baghdadi from the armed group.
Sources within the Anbar Operations command told Al Jazeera that 20 Iraqi troops had been killed in battles - a number disputed by an official of the US military's Central Command (CENTCOM). The official said there were "almost no casualties" on the part of the Iraqi forces but "many casualties on the enemy side".
CENTCOM oversees the US-led coalition air strikes against ISIL in Iraq and Syria.
The Iraqi army recently managed to open a corridor to evacuate residents from the besieged city of Baghdadi, where civilians had been trapped without food and water. A few families remain in the city and the situation there has been described as "dire".
Baghdadi is not far from Ayn al-Asad airbase, which houses American forces and their coalition partners.
It is the second largest US military airbase in Iraq.
Earlier on Thursday, ISIL sent a military vehicle with suicide bombers to try to get to one of the gates of the airbase and detonate the explosives, Al Jazeera's Jane Arraf, reporting from the capital, Baghdad, said.
"While the truck did not reach the gate, it did come to a few kilometres of one of the main gates of that base where they were repulsed by Iraqi forces," she said.
In another development, ISIL has released 30 men it had captured near Tikrit, according to Anwar Assi al-Obeidi, an influential local sheikh.
ISIL fighters reportedly captured 118 men and nine boys on Sunday from Rubaidha village, east of Tikrit, and then released 21 of the men - leaving 97 men and nine boys still in captivity.
Most of those captured have relatives fighting against ISIL, Obeidi told Al Jazeera on Thursday, adding that 600 members of his al-Obeid tribe have been killed by ISIL fighters since June.
A new UN report released this week documents widespread human rights violations committed by ISIL in Iraq between September and December last year.
"Members of Iraq's diverse ethnic and religious communities, including Turkmen, Shabaks, Christians, Yazidi, Sabaeans, Kakae, Faili Kurds, Arab Shia and others have been intentionally and systematically targeted by ISIL and associated armed groups and subjected to gross human rights abuses," the report says.
Meanwhile, the number of Christians abducted by ISIL in neighbouring Syria has risen to 220 in the past three days, as the group rounded up more hostages from a chain of villages along a strategic river, activists said on Thursday.
The Britain-based Syrian Observatory for Human Rights said the fighters picked up dozens more Christian Assyrians from 11 communities near the town of Tal Tamr in the northeastern Hassakeh province.
The province, which borders Turkey and Iraq, has become the latest battleground in the fight against ISIL in Syria.
It is predominantly Kurdish but also has populations of Arabs and predominantly Christian Assyrians and Armenians.
Source: Al Jazeera and agencies