Four people have been arrested for an alleged attempt to sabotage a stage of the Vuelta a Espana, Spanish police said on Tuesday.
Police said they were planning to spill hundreds of litres of a liquid similar to motor oil on the road during Monday’s third stage.
They were arrested on Saturday and are thought to be part of a group that is seeking the independence of Catalonia.
The four individuals were released on Tuesday pending further investigation.
They have been ordered to stay at least 500 metres away from the race.
Officers said they had found two barrels full of oil, which were connected to a pipe leading to a bridge above the planned route.
Monday’s third stage, won by defending champion Remco Evenepoel, saw the race leave Barcelona to head into the Pyrenees mountains.
The race, one of cycling’s grand tours, finishes in Madrid on 17 September.
