Britain's Prince William has spoken out on his desire to have children.

The royal - who married Duchess Catherine in April 2011 - revealed he and his wife are both keen to start a family but wouldn't comment on when it will be.

"I'm just very keen to have a family and both Catherine and I, you know, are looking forward to having a family in the future," he said, speaking on ABC News special The Jubilee Queen With Katie Couric.

However, when asked if he and Catherine - who was known as Kate Middleton before her wedding - have plans to start a family soon, he laughed and replied, "You won't get anything out of me. Tight lipped."

William, 29, isn't the only broody royal. His brother Prince Harry revealed he has always wanted children, but just needs to find the right woman.

Harry - who is believed to have recently reconciled with his on/off girlfriend Chelsy Davy - said, "I've longed for kids since I was very, very young. And so...I'm waiting to find the right person, someone who's willing to take on the job."

Meanwhile, William admitted juggling his royal duties with his life as an Air Force search-and-rescue pilot has been "difficult."

"It's a really difficult one because I really enjoy my time in the Air Force. And I'd love to continue it. But the pressures of my other life are building. And fighting them off or balancing the two of them has proven quite difficult."