A dense sandstorm engulfing parts of the Middle East left at least two people dead in Lebanon and hundreds suffering from respiratory problems on Tuesday, as officials warned residents to stay indoors.

A dense sandstorm engulfing parts of the Middle East left at least two people dead in Lebanon and hundreds suffering from respiratory problems on Tuesday, as officials warned residents to stay indoors.

Large parts of Lebanon, Syria, Palestine and Cyprus were shrouded in a thick cloud of dust from the storm that began sweeping into the region on Monday.

The Lebanese health ministry said two women had died at hospitals in the Bekaa Valley region because of the storm.

"The number of cases of choking and shortness of breath caused by the sandstorm has risen to 750," the ministry said.

Police distributed face masks on city streets as authorities warned people suffering from health problems, the elderly and pregnant women to stay indoors.

Education Minister Elias Bou Saab ordered private schools across the country to close on Wednesday, calling on "school officials to respect this decision and to protect students from any danger", a ministry statement said.

Lebanon's weather service said the storm was expected to abate from Wednesday night.

Mouin Hamzeh, secretary general of Lebanon's governmental National Council for Scientific Research, said satellite images "clearly show that the sandstorm came from northern Iraq in the direction of central and northern Lebanon, north and east Syria, and southern Turkey."

"It usually happens twice or even three times a year in Lebanon but during spring, March and April, and the unusual thing today is the density of the storm," he told media outlets.

In neighboring Syria, the storm also swept across much of the country, reducing visibility everywhere from coastal Latakia province to eastern Deir Ezzor.

Syria's health minister urged citizens to "avoid prolonged exposure to the outdoors" and said hundreds of people had been treated for cases of asthma and other respiratory problems.

The effects of the storm had also reached Cairo, where the city skyline was obscured by a thick haze.

Wahid Saudi, a top official at Egypt's weather authority, said the dust had blown in from the eastern Mediterranean region and was expected to clear after several hours.