The ceremony for Archie Harrison Mountbatten-Windsor was conducted by the Archbishop of Canterbury Justin Welby in the castle's Private Chapel, Buckingham Palace says.

In accordance with royal tradition, the Lily Font and water from the River Jordan were used during the christening, and Archie wore the handmade replica of the royal christening robe.

The Duke and Duchess of Sussex shared two official photographs of the occasion on their official Instagram account on Saturday, taken in Windsor Castle's Green Drawing Room and Rose Garden

One family portrait included Prince Charles, Meghan's mother Doria Ragland and Prince William and his wife, Kate.

The late Princess Diana's sisters - Harry and William's aunts - Sarah McCorquodale and Jane Fellowes also posed for the picture.

A black-and-white photograph showed Archie in his parents' arms in the Rose Garden.

Buckingham Palace has not disclosed who Archie's godparents are.

Some newspapers carried reports criticising Harry and Meghan for accepting public funds for their wedding and for renovations for their new house but denying the public a view of the baby and his parents arriving at the ceremony.

William and Kate organised media facilities for the christenings of their three children, in which arrivals at the church were filmed.

Royal fans gathered near Windsor castle on Saturday, some with banners and flags, despite the well-publicised private nature of the occasion.

"I think it's very hurtful to the fans, very, very hurtful," 63-year-old Cardiff resident Anne Taley said.

"We've had the fingers, we've had the toes. When are we ever going to see the baby?" she added, referring to previous discreet pictures posted by the royal couple.

Cheryl Bolson, 53, from Southampton, said she accepted the christening was a private, family event but felt the public should have been included.

"It would be nice if they were to come out afterwards and just maybe show the public that the baby's been christened," she said.

Harry and Meghan married at Windsor Castle, west of London, last year. Archie is seventh-in-line to the British throne.

Australian Associated Press