BAGHDAD — Iraq's prime minister said on Monday that he has retired 24 Interior Ministry officials as part of efforts to restructure the country's security apparatus and enable it to better confront the threat from the Islamic State militant group.

Haider al-Abadi's announcement came as fighters with the Sunni extremist group attacked a police checkpoint near Iraq's border with Syria, killing at least 15 Iraqi officers in an assault that underscored the depth of the country's turmoil in the face of the IS group's onslaught.

The retirement of two dozen interior ministry officials is part of al-Abadi's efforts to "restructure the security forces and make them more effective in the face of terrorism," according to statements on his official Twitter and Facebook pages. Al-Abadi, who became Iraq's prime minister in September, has already retired a number of senior military officials as part of his push to reform the force. Monday's statements did not identify the individuals or the ranks of officials sent into early retirement.

The fall of Iraq's second-largest city, Mosul, in June was a turning point in Iraq's war against the jihadi group that calls itself the Islamic State. The U.S.-trained Iraqi military, harassed for months by small-scale attacks, buckled almost instantly when militants advanced on the city. Commanders disappeared, pleas for more ammunition went unanswered and in some cases, soldiers stripped off their uniforms and ran from the fight.

Since then, U.S.-led coalition airstrikes have served to reinforce Iraqi and Kurdish security forces as they battle the Sunni militants, but major victories have been sparse.

Monday's deadly attack on the checkpoint near the Syrian border took place in the town of al-Walid, according to a senior army official. At least 15 Iraqi border policemen were killed, the official said, and at least five officers were wounded. A government official in Iraq's Anbar provincial council confirmed the report. Further details were not immediately available.

In its blitz earlier this year, the Islamic State group seized most of the border crossings between Iraq and Syria. It also overrun a large part of Iraq's Anbar and Ninevah provinces and now controls about one-third of both Iraq and Syria.

Also Monday, the U.N. Assistance Mission for Iraq said that 1,232 Iraqis were killed and 2,434 were wounded in violence and terror attacks in November. Of those killed, at least 296 were members of Iraqi and Kurdish forces, as well as militias who fight alongside the troops.

The figures were a slight decrease from October, when the U.N. said at least 1,273 Iraqis had been killed.

Also last month, at least 402 people were killed in western Anbar province, according to the provincial Health Directorate, the U.N. mission said. Most of the victims died in the provincial capital of Ramadi, a battleground between the IS group and Iraqi troops. In Baghdad province, at least 332 people were killed in November, the U.N. said.

And in the Shiite town of Balad, 80 kilometers (50 miles) north of Baghdad, at least eight people died and 20 were wounded Monday after mortar shells hit a cluster of homes and a small market, police officials said.

All officials spoke on condition of anonymity because they were not authorized to talk to media.

Those killed in Balad included a woman and a child. The town has lately seen heavy clashes between Islamic State militants and Iraqi forces.