Teams sail down Seine in rain-soaked Olympics opening ceremony

Long queues had formed at access points along the Seine hours before the start of the parade.

After passing scanners and checkpoints, the first arrivals discovered the numerous floating stages installed in the river channel and bridges that have been festooned with flags and the pink-and-purple colours of the Games.

"The atmosphere is really friendly," said 75-year-old Frenchman Jean-Yves Herve, who watched the show with his granddaughter.

"There are lots of foreigners, we're enjoying it. It's good for France."

French security forces are on their highest alert to prevent terror attacks from spoiling the start of the first Olympics in Paris in 100 years, while acts of sabotage from hostile foreign powers were also a known risk.

French officials refused to comment on the identity of those responsible for the rail sabotage who appear to have had a sophisticated understanding of the network.