Prince Harry called on technology companies to be more transparent about issues affecting children as he and his wife Meghan made their first public appearance on Tuesday since her father was arrested on suspicion of possessing child sexual abuse material.

Harry delivered the remarks at the European Parliament in Brussels during the inauguration of a memorial honouring children who died after suffering harm linked to social media. The installation, called the Lost Screen Memorial, features replicas of oversized smartphones, each displaying a photograph of a deceased child on its home screen.

Meghan, the Duchess of Sussex and formerly known as Meghan Markle, was initially scheduled to speak alongside Harry but later withdrew because she was not emotionally strong enough, according to a person familiar with her decision. However, she accompanied her husband to the event.

The allegations against her father, Thomas Markle Sr., emerged last month. He was ordered to jail on Tuesday after removing an electronic monitoring device from his ankle, days after being charged with possessing child sexual abuse material.

Appearing emotional during his speech, Harry urged social media companies not to expose children to content that they would not want their own children to see.

He also called for greater transparency and cooperation from technology firms, particularly in helping parents access their children's devices and social media accounts to understand what they experienced online.

"For many parents, even though their child killed themselves, they've had to wait years – in some instances, eight years – to get access to their child's phone," Harry said.

He added that some parents had been prevented from discovering the circumstances of their children's deaths because of companies' privacy policies, saying such restrictions were unacceptable.

"That cannot be right," he said.