Iraqi lawmakers are urging the country's new prime minister to quickly assign the critical posts of defense and interior minister which will spearhead domestic efforts to combat the violent Sunni militant advance.

Addressing lawmakers late Monday, Prime Minister Haider al-Abadi requested an additional week for the selection of these positions.

Sunni lawmaker Hamid al-Mutlaq said expressed Tuesday his concern over the vacant posts, calling on al-Abadi's government to "prove its credibility and good intentions." Salim al-Muslimawi, a Shiite lawmaker from Babil province, said any further delay in naming a defense and interior minister risks making the government appear weak and divided.

The United States launched airstrikes in Iraq on Aug. 8 in hopes of boosting the waning efforts of Iraqi and Kurdish forces fighting militants with the Islamic State group.