The reviews are almost universally glowing and the queues are dutifully forming at Apple stores across the world, but in France the much-hyped release of the iPhone 5 could be stymied by strike action.

Unions have called for a work stoppage for Friday in the firm's 13 French stores on what was set to be the shops' busiest day of the year, with hordes of avid Apple fans keen to get their hands on the phone's latest incarnation.

The strike call came after negotiations between unions and management broke down late on Thursday afternoon.

Apple management has resisted pay rises by arguing that the French branch of the firm lost 10 million euros ($13 million) last year.

The strike was called by Sud, the smaller of two unions represented in the firm here, which said that management offered lunch vouchers but had not moved on demands for an improvement in monthly pay and the payment of a 13th month of salary, which is a common perk in France.

It was not immediately clear how many of the 1,500 French workers of the world's most valuable company would refuse to show up on Friday to deal with the frenzy that usually accompanies an iPhone release.

This year it is likely to be even more frenetic than usual, with some analysts predicting Apple could sell 10 million units across the world in the opening days and 50 million before the end of 2012.

Workers at the Apple store near the Paris Opera, where around 50 people were queuing outside Thursday to make sure they would be first through the door the next morning, insisted their shop would open.

"I will be here tomorrow at 8:00 am, strike or no strike," said one young assistant, who like most of the workers here was dressed in a blue sweatshirt.

He declined to give his name as store employees are forbidden to speak to the press by the firm, which expects fierce loyalty from its employees.

The store manager refused to even meet an AFP journalist, referring him to Apple's press centre. The press centre has declined all week to answer AFP's repeated requests for information about the union negotiations.

Several of the dozens of workers in the Opera store were wearing a green bracelet with the word "Believe" emblazoned on it.

"We wear it to show we support the demands being made by the unions," said one worker. "The managers haven't said anything about this to us. But I'm pretty sure that they are taking note of who is wearing it."

The customers queuing outside were also confident that they would not be greeted by shuttered windows and closed doors on Friday morning.

Sylvain Gautier, a 38-year-old Paris civil servant who admits to being an Apple addict, was number four in the queue after arriving at 6:00 am on Thursday.

"They're smart people. Even if they go on strike they will keep the store open," he said, adding that he saw the workers' demands as legitimate.

The man at the top of the queue, 19-year-old Italian Anthony Shahir, a DJ whose alias is Anthony Fitch, could not even imagine the idea that he would not get his hands on the coveted device on Friday.

"I came from Rome with the sole aim of queuing up here to be first. I always want to be first. I was the first to get the iPhone 4 when it was released in Rome in 2004," he said as he waited patiently in warm September sunshine.