The workers are believed to have collapsed after the gas built up in poorly ventilated tunnels.
He made the comment on an official visit to Ethiopia, saying it could prove dangerous for a volatile region.
The media regulator said the ban would be in place "until further notice".
"This is the only hustle we know," miners tell the BBC as they try their luck at the site in Springs.
It is the latest twist over the fate of Lungu's body, which remains in a South African morgue since his death.
The troops, who landed at an airfield in Bauchi state, will not take part in combat operations, officials say.
Nigeria fans are still hoping Fifa may rule in their favour over allegations that DR Congo fielded ineligible players during Africa's 2026 World Cup play-offs.
Zimbabwe qualify for the Super 8s at the T20 World Cup as rain washes out their Group B game against Ireland.
Officials allege that an empty coffin was placed over concealed bags of charcoal in a hearse.
John Steenhuisen will not seek re-election as DA leader, leaving the race wide open for a successor.