JOHANNESBURG (Reuters) - Rescuers have retrieved another 13 bodies from a disused South African coal mine following a gas blast there around two weeks ago, police said on Friday, raising the confirmed death toll to 18.

More than 20 people were trapped underground in early February when a gas pipe exploded after they entered the mine to steal copper wire that supplies power for lighting and ventilation.

Rescuers had to abort their mission on Friday after bringing 13 bodies to the surface due to the presence of thick smoke, police spokesman Leonard Hlathi said. “By Monday they will go back again and continue with their job,” he told Reuters.

The Gloria Coal Mine in the eastern province of Mpumalanga is owned by Tegeta Resources and Exploration, which is under creditor protection after its owners, the Gupta brothers, found it difficult to continue doing business in South Africa following corruption allegations against them.

The brothers were accused of unduly influencing former president Jacob Zuma over political appointments and contract awards. Zuma and the Guptas deny wrongdoing.