In a landmark privacy battle, Apple has launched a legal challenge against the United Kingdom government's unprecedented demand to create a security "back door" in its cloud storage systems, the Financial Times newspaper has reported, citing people familiar with the matter.

The United States technology giant's legal appeal follows its recent withdrawal of Advanced Data Protection, or ADP, its highest-grade encryption system, from UK users, in response to a UK government order.

The removal of this protection means Apple can now access certain iCloud data, including iMessage backups, when legally required, which is something that is impossible under the end-to-end encryption that previously kept the data inaccessible, even to Apple itself.

The dispute highlights a longstanding conflict between governments seeking access to digital communications for security purposes and technology companies defending strong encryption for consumer privacy, reported Reuters. The UK's current demands, however, are considered unusually far-reaching, the news agency added.

Apple's decision to take its case to the UK's Investigatory Powers Tribunal is believed to be the first major legal challenge to the country's controversial 2016 surveillance law, which gives authorities broad powers to access encrypted communications.

The case, which could be heard this month behind closed doors, has drawn attention from privacy advocates who view it as a critical test of government overreach in the digital age. The tribunal has the power to overturn the order if it finds the government's demands unlawful.

The FT revealed that, last month, Apple had taken two significant steps: filing a legal appeal against the government order while simultaneously withdrawing its most secure online backup service from the UK market.

The company chose to remove the service entirely rather than comply with the government's Technical Capability Notice, or TCN, which it received in January.

The UK government maintains that Apple has still not fully complied with its demands, which would potentially allow the UK to access data from users in other countries, the FT reported.

The move has sparked international tension, with US President Donald Trump and his new intelligence chief publicly opposing the UK's stance and urging its reversal.

The US Director of National Intelligence Tulsi Gabbard warned that accessing US citizens' data would constitute an "egregious violation" of privacy and could violate the Cloud Act bilateral data agreement.

Both Apple and the Investigatory Powers Tribunal declined to comment on the case, the FT reported. A spokesperson for the UK's Home Office defended the government's position, saying privacy "is only impacted on an exceptional basis in relation to the most serious crimes and only when it is necessary".

The British government argues that bypassing encryption in messaging and backup systems is crucial for fighting terrorism and child abuse, putting pressure on companies like Apple and Meta to create access points.

However, cyber security experts counter that strong encryption remains essential to protect users from escalating online fraud and identity theft.