British royal Prince Harry has broken his silence on his sister-in-law Catherine, Duchess of Cambridge's pregnancy, insisting he's "thrilled" about becoming an uncle.

Prince William and his wife Catherine are set to become first-time parents in July (13), and they announced the news prematurely in early December (12) after the mum-to-be was hospitalised for extreme morning sickness.

Harry, who has been serving in the military since September (12), has yet to congratulate the pair in person, but in a rare new interview the 28 year old admits he can't wait to welcome the tot into the world.

He jokes, "Obviously I'm thrilled for both of them. It's about time. I spoke to my brother and her, and they're both very well and both very happy obviously."

However, he hopes the media will be respectful of the couple's privacy as William and Catherine try to raise a baby in the public eye.

He says, "I think it's very unfair that they were forced to publicise it when they were (sic), but that's just the media for you. I literally am very, very happy for them, but I just only hope that she and him - but mainly Catherine - hopefully that she gets the necessary protection to allow her, as a mother-to-be, to enjoy the privacy that that comes with. I seriously hope that's going to be able to happen."