Two small explosive devices have been detonated along a Spanish section of the Tour de France cycle race, Spain's interior ministry has said.
Cyclists had already passed when the blasts occurred
No-one was injured in the blasts, which officials said followed a phone call from the Basque separatist group Eta.
The small explosions occurred just outside the town of Belagua, 1km (half a mile) from the French border.
Eta has waged a violent campaign since the 1960s for an independent state in northern Spain and south-west France.
Officials said the devices, which included only "a small amount of explosives", were placed on either side of the road and hidden in plastic food containers.
They did not explode until some time after the cyclists had passed through the town, according to local media.
It is not the first time that Eta, which called off a ceasefire in June, has targeted the top cycling event to draw attention to its aim of achieving an independent Basque homeland.