Rescuers battled hazardous conditions Thursday at a coal mine in northern Iran where 26 miners died as attempts failed to save workmates trapped deep underground after an explosion. Hopes of finding nine missing miners alive were fading more than 36 hours after the blast Wednesday at the mine in Azadshahr in Golestan province, where three days of mourning were declared.

The rescue operation at the Zemestan Yort mine was hampered by poisonous gases that filled the tunnels as well as by fears of a further collapse. The removal of rubble blocking the tunnel was expected to finish by the end of Thursday, state television broadcaster quoted Labour Minister Ali Rabii as saying from the site. Iran's supreme leader Ayatollah Ali Khamenei offered condolences for the "very bitter" tragedy.

"Efforts by various organisations will be rewarded (by God). They (should) increase their efforts as much as possible," he said in a message.

President Hassan Rouhani also expressed sorrow for victims of the disaster, which has overshadowed his re-election campaign. Tasnim news agency quoted director of Iran's emergency services Pir Hossein Kolivand as saying that 26 bodies had been recovered from the mine. Sadegh-Ali Moghadam, emergencies director in Golestan province, had said earlier that 21 victims were found at a depth of 600 metres (yards) and rescue teams had descended 1,400 metres into the tunnel where the blast happened. The hope of finding the remaining miners alive "is now minimal," he told state IRNA news agency.

Copyright Agence France-Presse, 2017