The row began in February when it first emerged the government was seeking the right to be able to access data protected by ADP, using powers granted to it under the Investigatory Powers Act.

The Act allows it to covertly compel firms to provide information to law enforcement agencies.

ADP allows users with iCloud accounts and storage to secure photos, notes, voice memos and other data with end to end encryption, meaning no-one but the user - not even Apple - can access it.

Getting round that would involve the creation of a so-called "backdoor" - a capability some fear bad actors would ultimately be able to exploit.

At the time Apple reiterated its long-standing commitment not to weaken the privacy or security of its systems.

"As we have said many times before, we have never built a backdoor or master key to any of our products, and we never will," a spokesperson told the BBC.

Later in February the row escalated, as Apple announced it was pulling ADP in the UK.

Shortly after that, the BBC learnt Apple was taking legal action by appealing to the Investigatory Powers Tribunal to try to overturn the government's demand.

On its website, the Tribunal lists a hearing to be held before its president Lord Justice Singh on Friday afternoon.

The listing makes no mention of Apple or the government, nor has the Tribunal confirmed if they are the parties involved - however a source familiar with the matter has indicated that is the case, as was first reported by Computer Weekly, external.

In the statement it issued in February, Apple said it regretted the action it felt it had been forced to take.

"Enhancing the security of cloud storage with end-to-end-encryption is more urgent than ever before," it said.

"Apple remains committed to offering our users the highest level of security for their personal data and are hopeful that we will be able to do so in future in the UK."

In a previous statement, a Home Office spokesperson said: "The UK has a longstanding position of protecting our citizens from the very worst crimes, such as child sex abuse and terrorism, at the same time as protecting people's privacy.

"The UK has robust safeguards and independent oversight to protect privacy and privacy is only impacted on an exceptional basis, in relation to the most serious crimes and only when it is necessary and proportionate to do so."