The Apple Watch debuted in selected global markets Friday with sales limited to clients who had pre-ordered online, making the launch a relatively low-key affair compared to tech titan's usual fanfare.

Previous roll-outs of the firm's products such as the iPhone and iPad have generated queues outside stores more than a week in advance, with many customers wearing fancy dress while waiting for shop doors open with loud whoops and cheers.

But official Apple outlets in the Japanese capital were quiet Friday, with none stocking the smartwatch that the California company is hoping will give it a leading position in the world of wearables.

Instead, initial sales of the hi-tech wristwear were being restricted to specialised and luxury boutiques in the US, Canada, Britain, France, Germany, Australia, Japan and Hong Kong.

Yet though that first wave of watches were intended to be reserved to pre-ordered models, at least one non-Apple outlet in Tokyo was selling them to walk-up customers, an AFP reporter witnessed.

- Online chatter entices fans -

Twitter users spread word that a store in Tokyo's Akihabara electronics quarter had gotten deliveries of the watch, leading several intrepid people checking the rumour out to walk away with Apple Watches of their choice -- and without waiting in line.

Similar online chatter in Paris that luxury boutique Collette might have a thousand of unclaimed watches to sell to walk-up customers produced a line of some 200 people outside its doors Friday morning.

"Do you know if they'll have any in stock?" a hopeful customer named Franck asked other members of the Paris queue.

Some of those Parisian enthusiasts perched atop stools or on lawn chairs said they began forming line outside the ritzy central Paris shop on Wednesday afternoon.

"I lined up at the Opera Apple Store for the iPhone 4, iPhone 5 and iPhone 6, so this is a bit of a change of pace," mused one waiting buyer named Michael.

As the case in Asia, most people queueing in Paris were male. But irrespective of gender, all clients who got their hands on a watch declared themselves pleased.

"I'm happy. I want to wear it all the time," said Makoto Saito, a 23-year-old who appeared at a store in the chic Omotesando area, wearing a giant cardboard Apple Watch on her head.

Saito said she took the day off work to pick up the gadget.

Takuya Kajigaya, 32, said he was "thrilled" with his purchase.

"I want to make phone calls (with the watch) once I'm back home," he said, adding it would be a little embarrassing to talk to the device on his wrist.

While most buyers at the Softbank store in Tokyo's posh Ginza district pre-ordered the watch, 39-year-old programmer Yuichiro Masui said he had been waiting outside since Thursday night.

"I want to try the fitness application because I'm concerned about my weight," he said.

- 'Give it time' -

In China, which is expected to be a key market for the item, new owners went online to give their views.

"It is awesome! The Apple ecosystem is so strong, a large batch of applications can be used on the Apple Watch," said one happy recipient on the country's Twitter-like Sina Weibo.

Another posted: "Have received the Apple watch, have done some research but still couldn't get used to it. Give it time, I really like it!"

Apple says the watch will connect wirelessly to a user's iPhone and will be the interface for messaging, calls and apps, especially ones geared toward health and fitness.

Users can also send a real-time display of their heartbeat to another Apple Watch.

Despite the excitement expressed by succesful and thwarted clients, their enthusiasm won't guarantee success of Apple's newest product.

Sony took its SmartWatch to market several years ago, and rivals Samsung and Huawei are preparing roll-outs of their own into the still largely under-developed sector.

"For Apple's watch to really kick start this category, it would need to tackle three issues: the design, the relevance/applicability and the price. If Apple get the first two right, the price issue would take care of itself , said Imran Choudhary, telecoms analyst at Kantar Worldpanel.

"No doubt loyal Apple fans will be buying this as soon as possible. But on the application and usability, will the ordinary iPhone owner see enough benefit? The answer lies in the apps that are being developed."

Prices for the Apple watch start at $349, with a limited-edition gold version costing $10,000.