Hundreds of people have queued outside Apple stores in Asia and Europe to buy the new iPad2.
In the UK several people had queued overnight outside Apple's Regent Street store for the new tablet computer, introduced a week earlier in the US.
Analysts estimate about a million tablets were sold in the first weekend and this week the rollout was extended to 25 countries including most of Europe, Australia, New Zealand, Canada and Mexico.
Although the Japanese launch has been delayed, Apple says component shortages resulting from the earthquake there are not to blame.
Several key components in the iPad 2 come from Japan, including the battery and the flash memory used to store music and video on the device, according to IHS iSuppli.
Some non-Apple outlets in New Zealand and London said they had only been allocated a dozen iPads apiece.
Fears have been raised that shortages in the US could be repeated abroad, although a source at a UK retail chain told Reuters the reason might be that Apple wants to be seen to sell out rather than any shortage of parts.
32-year-old financial adviser Jewels Lewis was at the head of a 300-strong queue at Apple's Regent Street store, after being fourth in line for the original iPad a year ago.
He had been waiting since 7.30am the previous day for the 5pm sale and admitted to London's Evening Standard he had missed his son Shyam's 12th birthday to queue for the £399 gadget.
Canadian backpacker Alex Lee was the first to claim his iPad 2 at the Apple store in Sydney where he had been in line for two nights.
"If it wasn't for the iPad, I wouldn't be in Australia right now," said Lee, who had already bought an iPad 2 in the United States.
"It's like a habit. I've also lined up on Regent Street in London for the iPhone."
In Frankfurt, Germany, about 80 people were waiting outside the Apple store with most gathering on the morning of the sale.
Thorsten Schumann, 30, said: "I was in the States and I held an iPad 2 in my hand, and now I want to have one."
However in Nokia's homeland Finland, where Apple has made less of an impression than in many other markets and has no flagship stores, no queues were to be seen outside reseller outlets in below-freezing temperatures.
In Asia, the iPad 2 will be officially available in Hong Kong, South Korea, Singapore and other countries in April.
In Hong Kong, iPads purchased in the United States are already on sale for hefty mark-ups.
Analysts expect the iPad2, a thinner and faster version which features two cameras for video chat, to sell 30 million or more this year, generating close to $20 billion in sales.
The first iPad, which went on sale a year ago, sold 500,000 units in the first week and crossed the 1 million unit mark in 28 days.
Nearly 15 million iPads were sold in nine months of 2010 - two or three times as many as analysts had predicted.
Apple chief executive Steve Jobs said the company was "working hard to build enough iPads for everyone" as the company struggled to meet US demand.
Delays have been relatively harmless to Apple while it enjoyed a near-monopoly in the tablet market it created with the original iPad last year, but rivals are rushing to market with their own offerings to cash in on the trend.
Samsung Electronics and Motorola have tablets on the market and Blackberry-maker Research In Motion and Hewlett-Packard Co will release theirs in coming months.