A gas explosion in a coal mine in Iran’s South Khorasan Province killed at least 31 people and injured 16, the country’s interior minister Eskandar Momeni told state media on Sunday.

Local media had reported earlier in the day that 51 people were killed following the accident they said was caused by a methane gas explosion in two blocks, B and C, of the privately-owned mine operated by the Madanjoo company.

Momeni added that 17 miners were still missing and their fate remained unknown as rescue teams were still 400 metres away from their likely location. They were expected to reach it by tomorrow after removing rubble and excess gas.

There were 69 workers in the blocks at the time of the explosion, state TV reported.

“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,” the governor of South Khorasan Province Ali Akbar Rahimi told state TV on Sunday.

The mine went through inspections last month and complied with all safety regulations, labour minister Ahmad Meydari told state media, denying any case of negligence and adding that such “sudden events also happen in the most advanced mines globally”.

An investigation into the incident has been ordered by the country’s public prosecutor.

The explosion occurred at 9 p.m. (1730 GMT) on Saturday, state media said.

Iran’s Supreme Leader Ayatollah Ali Khamenei and President Masoud Pezeshkian sent their condolences to the victims’ families.