By Maher Chmaytelli

BAGHDAD (Reuters) - Islamic State claimed a series of suicide attacks that killed at least 14 people south and west of Baghdad on Monday as a U.S.-backed campaign to capture Mosul, the insurgents' last urban stronghold in Iraq, made slow progress.

The attacks showed that even though the jihadists have been losing territory over the past year - and face a big battle to hold Mosul in the north - they retain the ability to strike across Iraq, even in the central areas near the capital.

Eight people were killed and about 25 wounded when two suicide bombers blew up their cars at police checkpoints in Falluja, a former Islamic State stronghold west of Baghdad.

A suicide bomber killed six people and wounded another six in a rural area near Kerbala, a holy Shi'ite city south of the capital where preparations are underway for a major religious event.

The casualty figures were obtained from police sources.

The bomber near Kerbala blew himself up west of the city where hundreds of thousands of Shi'ites were gathering to mark Arbaeen, which comes at the end of a 40-day mourning period to mark the death of Imam Hussein, the grandson of the Prophet Mohammed.

Islamic State has been retreating since last year and was driven out of Falluja in June. In Iraq, the group continues to control territory west of Mosul, the northern city from where it declared a "caliphate" over parts of Syria and Iraq in 2014.

With air and ground support from the U.S.-led coalition, the offensive on Mosul entered its fifth week on Monday with Iraqi government forces still trying to consolidate gains made in the eastern edge of the city that they breached end of October.

A mixed Kurdish and Yazidi armed force known as the Sinjar Resistance Unit said on Monday it had dislodged the jihadists from five Yazidi villages west of Mosul in an advance that began on Saturday.

Islamic State fighters overran the five villages in 2014 when it swept over Sinjar mountain and the surrounding region inhabited by Yazidis, killing, capturing and enslaving thousands from the Iraqi religious minority.

U.S.-backed Iraqi and Syrian Kurdish forces took back the city of Sinjar and most of the mountain area in 2015 but the region south of the mountain remained in the hands of the ultra-hardline Sunni Muslim militants.

Iraqi government forces, who are supported by Kurdish peshmerga fighters and Iranian-backed Shi'ite militias, are yet to cross into the northern and southern limits of Mosul, where more than a million people are thought to be still living.

About 54,000 have been displaced by the fighting from villages and towns around the city to government-held areas, according to U.N. estimates.

The figure does not include the tens of thousands of people rounded up in villages around Mosul and forced to accompany Islamic State fighters to cover their retreat toward the city.

(Editing by Pravin Char)