At least 17 Iraqi soldiers were killed in suicide attacks by ISIS militants in the northern city of Mosul on Sunday, according to a local security official.

A bomber rammed his explosives-laden vehicle into Iraqi forces in northwestern Mosul, killing six soldiers and injuring four others, the official said on condition of anonymity due to restrictions on speaking to media.

Three soldiers were also killed when another bomber detonated his vehicle at anti-terrorism forces in al-Najjar district, northwest of Mosul, the official said.

Two suicide bombings also killed eight soldiers and injured nine others in the war-ravaged city, he said.

"The terrorist organization is using the bad weather conditions to carry out suicide attacks against Iraqi forces," the official added.

In February, Iraqi forces -- with air cover provided by a U.S.-led coalition -- began fresh operations aimed at purging ISIS from western Mosul, the terrorist group’s last stronghold in northern Iraq.

The offensive came as part of a wider campaign launched last October to retake the entire city, which ISIS overran -- along with other parts of the country -- in mid-2014.