Prince Harry has confirmed US actress Meghan Markle is his girlfriend, in a statement from Kensington Palace attacking the media for subjecting her to a "wave of abuse and harassment".
The statement said the couple were "a few months into a relationship" and it was "not right" that Ms Markle should be subjected to such treatment.
It said the prince rarely took formal action over "fictional stories".
"But the past week has seen a line crossed," it added.
In recent days a number of newspapers have carried front page stories about the 35-year-old actress, best known for playing Rachel Zane in the TV drama Suits.
The statement issued by the prince's communications secretary said: "His girlfriend, Meghan Markle, has been subject to a wave of abuse and harassment.
"Some of this has been very public – the smear on the front page of a national newspaper; the racial undertones of comment pieces; and the outright sexism and racism of social media trolls and web article comments.
"Some of it has been hidden from the public – the nightly legal battles to keep defamatory stories out of papers; her mother having to struggle past photographers in order to get to her front door; the attempts of reporters and photographers to gain illegal entry to her home and the calls to police that followed; the substantial bribes offered by papers to her ex-boyfriend; the bombardment of nearly every friend, co-worker, and loved one in her life."
The 32-year-old prince has long had an uneasy relationship with the press, having grown up aware of the impact that intense media intrusion had on the life of his late mother, Diana, Princess of Wales.
When he was 20, he was caught up in a scuffle with a paparazzi photographer outside a London nightclub.
In 2012, naked photographs of him in a Las Vegas hotel room were published online and on newspaper front pages, prompting a complaint to the Press Complaints Commission.
But he has also attracted positive coverage of his charitable interests and military service.