LOUDENVIELLE-LE-LOURON, France, July 23 - Buses belonging to four teams on the Tour de France have been searched by French customs, an Astana team spokeswoman said on Monday.

Officials searched the buses of the Astana, Discovery Channel, CSC and Rabobank teams, she said.

"I am currently in the bus," Corinne Druey told Reuters over the telephone. "They have searched the whole bus, they have searched the riders' personal effects."

Druey said the search took place on a parking lot on the A64 motorway just outside the southwestern town of St Gaudens.

"They have found some prescription medicines but they did not take anything from the bus," she added. "The buses from the French teams have not been stopped, the customs have let them go.

"Now we are late. We have not reached the finish line yet."

CSC team manager Alain Gallopin said such searches were not unusual.

"I know about that," he told Reuters. "It has happened to us many, many times."

St Gaudens is some 30 km from the Spanish border.

Monday's 15th stage of the Tour was taking the riders, with Rabobank's Michael Rasmussen in the leader's yellow jersey, over 196 kms from Foix to Loudenvielle.