Another 24 miners were believed to be trapped inside after the explosion struck a mine in Tabas, some 335 miles southeast of the capital, Tehran.

It is not clear how many, or if any, people are believed to be trapped now that a rescue operation is under way.

There were 69 people working in the mine at the time of the blast, which happened late on Saturday, Iranian state TV has reported.

The accident was caused by a methane gas explosion in two blocks, B and C, of the mine run by the Madanjoo company, state media said.

Of the 47 workers who were in the block B, 30 died and 17 were injured, local governor Ali Akbar Rahimi said earlier.

The rescue operation at block B is now completed

Methane density in block C is high and a rescue operation that is under way there is expected to take three to four hours, Mr Rahimi said.

"76% of the country's coal is provided from this region and around 8 to 10 big companies are working in the region including Madanjoo company," Mr Rahimi said.

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Iran's new president Masoud Pezeshkian, preparing to travel to New York for the United Nations General Assembly, said he ordered all efforts be made to rescue those trapped and aid their families.

He also said an investigation into the incident had begun.

This is not the first disaster to strike Iran's mining industry.

In 2017, a coal mine explosion killed at least 42 people, while 11 workers were killed in two separate mining incidents in 2013.

Lax safety standards and inadequate emergency services in mining areas are often blamed for the fatalities.

Iran annually consumes some 3.5 million tons of coal but only extracts about 1.8 million tons from its mines per year. The rest is imported, often consumed in the country's steel mills.