The Prince of Wales has praised military commanders for acknowledging the threat climate change poses to world stability by featuring the issue in a major exercise.

Charles said that their decision was of "enormous importance" and mirrored his own belief that future global problems would come from catastrophic events like sea level rises or droughts.

His comments came when he met troops from eight countries, including the UK, US and France, in New Zealand tasked with helping a fictitious government bring back stability after a rebel group divided the country along ethnic lines - with the issue exacerbated by a tsunami.

Charles, recently made a Field Marshall of the New Zealand Army, visited the military personnel at the headquarters of exercise Southern Katipo in Westport.

Wearing a beret and a New Zealand Defence Force NZDF camouflage uniform he told some of the troops: "One of the reasons I've been trying to go on about climate change for so long is unfortunately it's a threat multiplied.

"I'm glad to see that at last various military people are taking this seriously.

"Because I've always felt the threat is going to come more from mass migration, conflict over scarce resources, sea level rise, a drought, floods - every kind of other.

"The fact that you're practising all this is obviously going to be of enormous importance."

Exercise Southern Katipo, targets the fictitious Pacific island of Becara hit by political unrest and split along ethnic lines by a militant force that has forced a group of people on to a peninsula which is then hit by a tsunami.

More than 2,000 army, naval and airforce personnel from Australia, Canada, Fiji, France, Papua New Guinea, Tonga, the US and UK have been rescuing mock tsunami victims and carrying out other humanitarian and support work during the exercise which runs until the end of the month.

Charles, a former Royal Navy helicopter pilot, told the assembled troops that 40 years ago he had been a "small cog" in a military exercise and made them laugh when he said: "But whatever the case, you can always blame me if it goes wrong. I'm bound to have caused some awful hold-up just at the crucial moment."

During his visit to the exercise headquarters Charles clambered into the cockpit seat of a RNZAF's NH90 helicopter used for a number of roles from supporting troops on the battlefield to carrying out search and rescue duties.

He also met military medical staff in a field hospital and chatted to bomb disposal experts from Canada and New Zealand.

Charles is on a 12-day tour of New Zealand and Australia with Camilla and their day began in the town of Nelson where they were welcomed by thousands of well-wishers who turned out to catch a glimpse of the royal visitors.

Babies, corgis and a little boy dressed as a guardsman were sights that greeted the Prince and Duchess as they walked through the streets.

Later Charles put on a white lab coat to learn about developments in the world of algae and invertebrates as he explored sustainable seafood at Nelson's Cawthron Institute.

He looked through microscopes at algae used to produce antioxidants, chuckled at the appropriately-named multi-coloured algae disco, saw baby snapper and heard how Cawthron and research company Plant and Food Research were working towards making the seafood industry sustainable and clean with the ever-increasing population.

He even saw the first female scampi bred in captivity in New Zealand and in honour of the royal visit, Cawthron named her Camilla, which was met by laughter.

Outside the research centre the Prince met his former nursery nurse Jacqui Botting, 94, who is now being cared for at a nursing home across the road from the research centre.

Charles stopped to chat to the elderly woman who was sitting under a tree and clutching a card that had been signed by Charles and his siblings Anne and Andrew.

He affectionately touched her on the arm as they briefly said hello, and asked if she was keeping well.

Meanwhile Camilla revealed she has adopted a dog that had been tied to the central reservation of a motorway when she visited Wellington SPCA (Society for the Prevention of Cruelty to Animals).

At the centre the Duchess, who adopted two dogs from Battersea Dogs and Cats Home, placed a leaf on the tree of remembrance for her late Jack Russell Freddie who died in 2007 at the age of 21.

She later watched Arthur, a three-legged dog who had been rescued after being hit by a car, go through a "dog wash" - a car wash style machine.

Camilla joked: "Oh I've got to have a bath. I am going into the dog wash".

The Duchess also visited a women's prison in Wellington and met inmates going through a drug treatment programme. Camilla spent time with the prisoners learning how education, art, singing and poetry was helping them overcome their problems.