"I plan to remain active in writing, recording and other projects for a long time to come.
"My thanks goes out to my loyal and devoted audiences around the world. You will always have my appreciation for your support and encouragement. This ride has been 'so good, so good, so good' thanks to you."
The Grammy Award winning artist was scheduled to play at Mission Estate on March 17.
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However, SEL events manager Garry Craft said it was hoped an alternative act could be found to ensure that people did not have to change plans.
"It's extremely sad and this came from way out of left field. We were advised at midday of the situation so we've been assessing where we go from here.
"I have three plans I am working on in parallel - two would see a concert take place on March 17 and one would see us cancelling the Mission concert for this year, which for all involved is the last thing we want to happen.
"People have made plans and made bookings, so my first aim is to find a line-up that people would want to see so that they can continue on."
Mr Craft said plans would be put on hold for 48 hours whilst other options were worked on.
Although hotels here were expecting to receive booking cancellations following Mr Diamond's announcement, because the Mission concert fell on the same weekend as the Horse of the Year Show, they expected to recover any cancellations.
Omahu Motor Lodge manager Shay O'Brien said there would be about three cancellations.
"We had a lot of enquires for the concert but Horse of the Year is on at the same time."
Quality Inn Napier duty manager Giegrius Jankauskas agreed.
"We are already booked out for the Mission Concert period. We probably will receive cancellations but I don't think that will be an issue as we have Horse of the Year on the same weekend, so I have to say we will probably be full up."
Horse of the Year event director Dave Mee said from their perspective it didn't change a lot.
"It may mean that there are some people who weren't going to come who now can find accommodation and will come down."
Mr Mee said they had had some challenges around securing resturn flights out of the region, with a lot of their judges and other people having to fly out on Sunday.
