The Vuelta a Espana must improve rider safety in the final kilometres of stages to ensure there are no repeats of Steven Kruijswijk's accident, says race director Javier Guillen.
Kruijswijk was involved in a big crash in the closing moments of stage five on Wednesday as he collided with a bollard on the route, his fall bringing a number of riders down.
The LottoNL-Jumbo rider as a result was unable to contest the bunch sprint for victory in Lugo, while the melee that ensued delayed overall leader Darwin Atapuma.
Kruijswijk abandoned the Grand Tour following the accident, the Dutchman having broken his collarbone in the fall.
Questions were raised as to why the bollard was inside the barriers and why the teams and riders had not been made aware of it to ensure they all avoided it safely.
Guillen apologised for the oversight and vowed to improve safety standards going forward.
"Basically it's about repeating my apologies for yesterday," Guillen told Eurosport after a visit to the LottoNL-Jumbo team on stage six. "We're conscious that their main rider had to go back home after an extraordinary season.
"We have tried to strengthen our safety measures. We have already tried to improve them to quite a good level, but we still have to improve safety in the last three kilometres of racing which are particularly dangerous.
"It was a mistake, it was not a question of safety measures or if it was too tricky a circuit, it was a mistake not to alert them about this dangerous pole.
"What we have to do is raise up the safety in the final kilometre, we can't cover the whole stage but we have to be careful with the trickiest parts.
"We still don't know exactly what happened. Many people have worked or passed by that pole and nobody saw anything and so we're investigating that. If you pass by it and don't see anything we need to know why that's the case."