Stubborn robots that refused to dance were an ironic reminder of the scandal that has enveloped the French soccer team in South Africa as France celebrated its national pavilion day at the Expo on Monday with typical Gallic panache and the occasional hiccup.

France orchestrated one of the Expo's biggest and boldest national pavilion days by introducing cutting-edge humanoid robots. It also included Music Day, its annual music festival, in the event.

But things got off to an awkward start when the bots wouldn't budge.

A group of 20 "NAO" robots by Aldebaran Robotics stood outside the pavilion for 20 minutes as technicians scratched their heads and a crowd of onlookers grew increasingly impatient.

"Too slow!" screamed a Chinese man with his family.

The technical hiccup, although quickly resolved, evoked memories of the French squad's decision to cast its dire World Cup campaign into further chaos by refusing to train on Sunday in protest of the dismissal of star striker Nicolas Anelka for insulting coach Raymond Domenech.

Fortunately, for dignitaries including France's National Assembly President Bernard Accoyer, who was inside the pavilion at the time of the stalled show, the robots, which look like cute, toddler-size storm troopers, decided not to shame their benefactors by getting their act together.

They soon had onlookers awestruck with a synchronized dancing show that hinted at a brave new world of artificial intelligence. "We've got 20 robots dancing together here, which is very complicated," artistic manager Julien Gorrias told the crowd. "I know you're all (feeling) hot, but the robots are (feeling) even hotter."

Gorrias blamed the sweltering temperatures, which reached 28 C, the wind and the uneven surface of the performing stage for the technical snags.

The NAOs, which put on four shows on Monday during their public debut at the Expo, will return en masse next month and again in October, said Aldebaran CEO Bruno Maisonnier.

"What you are seeing now is better than science fiction," he said.

Seven of the robots will perform daily inside the pavilion beginning Tuesday and another three will do the same at the Paris City Pavilion inside the Urban Best Practices Area until the end of Expo.

The day's festivities included several performances of Douce France (Sweet France), a 15-minute musical produced by French actor Alain Delon.

"We presented this show because our pavilion wants to create a more artsy atmosphere and show how different cultures can influence each other and learn from one another," said communications officer Sissy Jiang.

Music fans were set to enjoy a concert by Matthieu Chedid at Mao Livehouse later in the evening as France brought another part of its culture to China.

Since 1982, France has celebrated June 21, the longest day of the year, with free outdoor music festivals.

Chedid, billed as France's top rock act, capped a two-day string of concerts that lit up Shanghai on Sunday and Monday as officials decided to double the length of the festival to catch the weekend crowd.

"Now the French and Chinese governments are in talks about making this an annual event," said Jiang.