The Health and Safety Executive has served a notice on the owners of the crane that collapsed in Croydon earlier this month.
Select Plant Hire, the Kent-based company that owned the tower crane that collapsed on the Croydon Park Hotel site on Saturday, June 2, injuring the crane driver and trapping three workers, has been served a notice banning them from erecting cranes without properly trained staff.
The HSE said the company was still allowed to operate its cranes, but they must do so with properly trained teams.
The safety watchdog said its investigation so far had found the top section of the crane had not been connected to the climbing frame but the HSE continues to investigate the incident.
A Select Plant spokesman said: "We take this extremely seriously.
"Safety is absolutely critical and we are determined to understand all the causes of this accident to ensure that we can prevent anything like this happening again.
"We believe our crane crews are adequately trained and accumulate extensive onsite experience before taking part in any crane climbing operations.
"Clearly, however, there are lessons to be learned from this incident and we are determined to learn those lessons - fast. We will not prejudge the outcome of the investigation and we continue to cooperate fully with the appropriate authorities.
"We are continuing to undertake climbing operations in accordance with the notice issued by the Health and Safety Executive and with their agreement."
A man was seriously injured and three others trapped 45 metres in the air for seven hours when the crane collapsed on top of the hotel.
Men working on the crane were heard screaming as the jib of the contraption crashed on to the roof of the Croydon Park Hotel on Altyre Road just after 2pm on Saturday, June 2.
The crane operator - trapped in the cab hanging from the side of the building - had to be winched to safety by a rescuer suspended by cables from a second crane.
But three others were stuck in the tower of the crane until about 9.20pm when they were rescued by fire crews.
Following the accident, 140 people were evacuated from the hotel and surrounding buildings while more than 50 fire fighters, six fire engines and four fire rescue units attended the scene.
Residents in the area reported hearing a crash "as loud as a bomb" and saw a cloud of dust and debris cover the surrounding streets.