The Duke and Duchess of Sussex have told New Zealanders "we are with you" as they signed a book of condolence for the victims of the Christchurch terror attack.

The Duchess wore a pair of earrings featuring a crossed feathers design given to her by the country's prime minister Jacinda Ardern. She was heard to describe Ms Ardern's response to the tragedy as "very impressive".

The Duke and Duchess greeted the New Zealand High Commissioner to the UK Sir Jerry Mateparae with the traditional Maori method of pressing noses together on Tuesday afternoon.

They both placed hand-tied bouquets of flowers outside the building in central London, adding to the pile of floral tributes which has grown since 50 people were killed after a lone gunman opened fire at two mosques during last week's Friday prayers.

The Duchess's featured lily-of-the-valley, hawthorn and ivy, while the Duke’s contained white roses, lisianthus, veronica and ferns.