Attending a reception on Tuesday as part of celebrations for the Queen's Diamond Jubilee, Mr Key said he chatted with many royals including the Duke and Duchess of Cambridge, Prince Charles and his wife Camilla, and Prince Harry.
"They all expressed their concerns about Christchurch, a number of them are looking forward to coming to New Zealand at some point in the future," Mr Key told reporters.
"William has been down to New Zealand twice now in the last few years and certainly Kate is very keen to come down and pay a visit, that was the first thing she mentioned, so it must be in their sights somewhere along the line."
Mr Key said that on hearing the news, he extended an invitation to William and Catherine.
In the meantime, Charles and Camilla are due in New Zealand in early November as part of a series of jubilee year tours of Commonwealth countries.
Members of the royal family were also able to reassure Mr Key of Prince Philip's improving health, after the 90-year old was admitted to hospital on Monday with a bladder infection.
"I think he's recovering well, but there's been a lot of pressure in the last few days," Mr Key said, adding that the Queen and her consort stood for more than four hours on board the royal barge in cold and wet conditions for Sunday's Diamond Jubilee pageant.
"I think it was Kate who said to me they tried to encourage him to go downstairs and have a cup of tea but they just wanted to be there and show their respect for everyone who showed out."
While it seems ailing health will prevent the Duke of Edinburgh heading to the southern hemisphere any time soon, another royal spouse seems set to keep clear of New Zealand for different reasons.
"I also spoke with Mike Tindall," Mr Key said.
"I said 'hello, I'm the New Zealand Prime Minister' ... he said `I didn't have a very good time in New Zealand'."
The husband of Zara Phillips, the Queen's eldest granddaughter, was England Rugby captain when the team arrived in New Zealand last year for the World Cup.
A short time into his country's October campaign the hulking centre was captured on CCTV canoodling with a blonde woman while on a night out with teammates who were also engaged in a dwarf-throwing event at a Queenstown nightclub.
Fallout from the drama included Tindall's ejection from the elite players squad and a STG15,000 fine.
