TEHRAN - The death toll from a blast at a coal mine in the eastern Iranian province of South Khorasan has risen to 51, the semi-official Tasnim news agency reported Sunday.

The number of those wounded in the explosion has reached 20, Tasnim quoted Mohammad-Ali Akhoundi, director general of the provincial crisis management headquarters, as saying.

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He added the blast, which occurred at the mine belonging to the Madanjoo Company in Tabas County at about 21:00 local time (1730 GMT) on Saturday, was due to a rise in the amount of methane gas in one of the tunnels, noting that the casualty count could rise.

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The injured have been transferred to medical centers, according to Tasnim.

The provincial authorities have declared three days of mourning in South Khorasan, according to the official news agency IRNA.

Earlier on Sunday, Akhoundi said 40 equipped teams were providing rescue services, putting the number of the rescuers at 100.

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Two ambulance buses and 13 ambulances were present. In a phone call, Iranian Interior Minister Eskandar Momeni ordered South Khorasan's Governor Javad Ghenaat to mobilize all provincial facilities and resources to accelerate rescue and relief operations, IRNA reported.

Elias Hazrati, head of the Iranian government's Information Council, said President Masoud Pezeshkian has issued a special directive to handle the incident, ordering relevant ministers to take necessary measures.