The iPhone 6s and iPhone 6s Plus are likely to break the record first weekend pre-orders of 10 million units achieved last year by the iPhone 6 and the 6 Plus. On a comparative basis, pre-bookings for the iPhone 5s and 5C were nine million units; the iPhone 5 touched the five million mark in just nine countries.

Both the iPhone 6s and the 6s Plus will go on sale from 25 September. However, this time around Apple has not provided figures for pre-orders in the first 24 hours.

The new iPhone models were showcased last week in an event in San Francisco with improved camera features, faster processor and the latest 3D Touch technology, which allows users to create short cuts to everyday tasks when pressed firmly on the screen.

"Customer response to the iPhone 6s and the iPhone 6s Plus has been extremely positive and pre-orders this weekend were very strong around the world," Bloomberg quoted Apple spokeswoman Trudy Muller as saying.

Unlike earlier occasions, pre-bookings for the iPhone 6s and the 6s Plus have been made available in China at the same time as other markets, as digital news outlet Quartz points out that China has a big share in the pre-orders of the latest iPhone models.

Greater China which includes Hong Kong and Taiwan accounts for as much as 20% of Apple's profits. As mainland China's population is about 40 times bigger than both the population of Hong Kong and Taiwan combined, Quartz says, it might have helped add as much as two million orders to its latest pre-bookings.

Apple is keeping up demand for its iPhones as more than 60% of the company's revenue has come from its handsets in recent quarters. The new iPhone models will be available in stores from 25 September in the UK, the US, Australia, Canada, China, France, Germany, Hong Kong, Japan, New Zealand, Puerto Rico and Singapore.