At least 5000 cases of respiratory problems resulting from dust storms have been registered in different parts of Iraq, the country's health ministry says.

Thick clouds of dust have engulfed most of Iraq since Wednesday night, prompting health authorities to call on people, mainly asthma patients, to stay indoors.

At least 2000 cases of breathing difficulties and one fatality have been recorded in the capital Baghdad, the health ministry's spokesman Saif al-Badr said, according to Iraq's state news agency INA.

The official did not elaborate on the circumstances surrounding the death.

"The total of the (storm-caused) asphyxiation cases in Baghdad and other provinces has exceeded 5000," al-Badr said.

"All hospitals, health institutions and emergency departments are on alert," he said.

Earlier on Thursday, INA reported that at least 1850 cases of breathing problems resulting from the storms had been recorded in five Iraqi provinces including the western province of Anbar.

The agency quoted a spokesman for Anbar's health authorities, Anis Qais, as saying that calls were made via local mosques and social media for sufferers of respiratory problems to head to health centres.

Iraq's Popular Mobilisation Units, a pro-state militia, meanwhile said their forces had repulsed an attack by Islamic State militants who had sought to take advantage of the bad weather in the western city of Falluja.

The Iraqi government declared military victory against IS in December 2017, three years after the radical group seized large swathes in the northern part of the country.

IS operatives, however, continue to carry out attacks in Iraq and neighbouring Syria.