The release of such details was "idiocy", he said, but Mr Key today responded by saying: "Well that bloke's an idiot, the Governor-General certainly isn't."
The royal visit is handled by the Department of Internal Affairs' royal visit office, and staff have used the official social media channels of Governor-General Sir Jerry Mateparae to tell New Zealanders where they will be able to see the young family.
The information included locations, times and the best place to stand to catch a glimpse, as well as maps of the routes they will take when meeting the public in various cities and town centres.
Details of private engagements and travel arrangements have not been publicly released.
Speaking today, Mr Key said he thought the criticism was "nonsense''.
"My understanding is Government House has been working with the Palace, they were quite aware of what was said.
"We've had a 30-year history of giving out indications of routes that the royal couple, royal family members, will take," he said.
And he hit out at the reliability of UK tabloids, pointing to the Daily Mail who labelled him a "galloping colonial clot" for a photograph with the Queen at Balmoral last year, in which the paper accused him of breaching royal protocols by releasing the image, when it had in fact been approved by the Palace.
"So I'm going to back Government House and the GG on this one and not the Daily Mirror," he said.
The Daily Mirror yesterday quoted Mr Davies as describing the information as a manual for terrorists, "nutters and fixated people" hoping to harm them.
"I'm appalled at the idiocy of any idiot who would publish this far in advance both route and location," he said.
"I find it almost unbelievable someone would do this. It's a manual and it goes against anything I believe in. Appalled is the word."
The tabloid called the information a "gift to terrorists" in its headline, and the Daily Mail followed suit, describing the notifications as a "manual for terrorists" that "could leave the couple at risk of an attack by terrorists or stalkers".
The royal visits office's media manager, Allen Walley, said the announcements were the result of months of planning and did not breach any regulations.
"There is no problem with it, all of this was planned well in advance, it was signalled to Kensington Palace and it was cleared with New Zealand police."
Although social media had advanced in recent years, giving public notification was business as usual for royal visits.
"Sending out the routes and public meeting places and so forth has been the norm with every royal visit to New Zealand for the last 30 years."
The Duke and Duchess will meet the public in Wellington, Blenheim, Auckland, Hamilton, Cambridge, Dunedin, Queenstown and Christchurch.
Read more: Royal route around NZ confirmed
The royal couple will fly in from Queenstown on the morning of April 14 before being driven by motorcade to the Christchurch City Council offices.
From there, they will be taken to the site of the CTV Building collapse, which came down in the February 22, 2011 earthquake, killing 115 people.
The Duke and Duchess will meet some of the families of victims at a memorial garden there before being taken through the transitional 'cardboard' cathedral.
After that will be the best chance for the public to get a glimpse of the famous couple when they walk through Latimer Square.
They will then meet former New Zealand cricket legends, including Sir Richard Hadlee for an event previewing the ICC cricket World Cup held in New Zealand next year.
From there they will open a new visitor centre at the Botanic Gardens in Christchurch before attending a lunch at the Air Force Museum in Wigram and then paying their respects at the RNZAF Memorial Wall.
They will then fly out of the city that afternoon.
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