Rainfall in the capital has this year been at its lowest level in a century, local officials say, and half of Iran's provinces have not seen a drop fall in months.

Faced with water shortages, the government has decided to cut off water supplies periodically to Tehran's 10-million-strong population to limit consumption.

On Friday, men and women gathered at the Emamzadeh Saleh mosque in the Iranian capital and said a special prayer to implore God for rain.

The women were veiled and prayed in a separate area from the men, in accordance with Islamic practice.

Tehran nestles on the southern slopes of the Alborz mountains and has hot dry summers usually relieved by autumn rains and winter snowfall.

The mountain peaks, usually already covered in snow at this time of year, are still dry.

Tehran is by far the country's biggest city and its inhabitants use three million cubic metres of water per day, according to local media.

Last week, President Masoud Pezeshkian cautioned that without rainfall before winter, Tehran could face evacuation, though he did not elaborate.

The government later explained that Pezeshkian had only wanted to alert residents that the situation was serious and was not presenting a concrete plan.

Of the five major dams supplying drinking water in the capital, one is empty and another is at less than eight percent of capacity, officials say.

The situation in the rest of the country is hardly any better. Local media reported that Iran's precipitation level this year has reached just 152 millimetres, a 40 percent decline compared to the 57-year average.