UK customers will have to pay up to £113 more than their US counterparts for the basic new iPhone 7.
The new Apple smartphone will have a starting price of £599 in the UK for the cheapest 32GB model while in the US it starts at $649 (£486) in states with zero sales tax.
The average combined sales tax across the US is around 6.5 per cent, meaning the average retail price would be $691 (£518) for the 32GB model.
This means the UK consumer will pay an extra £81 - almost 16 per cent more than the US average.
Apple chief executive Tim Cook unveiled the phone at an event in San Francisco alongside a new version of the Apple Watch, called the Series 2.
The new iPhone has been made water-resistant for the first time and has had the headphone jack removed and camera redesigned and improved.
Instead of a headphone slot, it will now come with earphones that fit into the phone's lighting port, currently used for charging and data transfer. However, an adaptor for traditional headphones will be included in the box.
Apple also revealed new wireless earphones, called AirPods, that will connect to both iPhone and Apple Watch remotely.
The new Series 2 watch has a greater focus on health and exercise tracking.
The Watch, iPhone 7 and iPhone 7 Plus will go on sale on September 16, with pre-orders for the devices beginning on Friday.
Mr Cook said of the smartphone: "It has become the industry gold standard.
"iPhone is the phone by which all others are measured and it has become a cultural phenomenon."
In July, the tech giant revealed it had sold the one billionth unit of the device, while Mr Cook said the Apple Watch was now the world's second most popular watch brand and most popular smartwatch.
The new iPhone models come in five colours: gold, rose gold, silver, black and a new jet black option.
