A six-year-old girl has caused a conundrum of global proportions after her attempts to send a message in a bottle to Norway ended up in New Zealand.

While on holiday with her grandparents on the north-east coast of Scotland, Keely Reid tossed a plastic water bottle into the Moray Firth in the expectant hope that the tide might carry it as far as the shores of Scandinavia.

However the girl and her family have been surprised to discover the bottle ended up travelling more than 20,000 miles in 47 days to be washed up on the beach of Whangamata on the north island of New Zealand.

The discarded bottle was apparently picked up by another six-year-old, James Wilson of Whangamata, who discovered the message inside and immediately wrote to Keely with proof that he had found it.

It is estimated that to find its way to New Zealand in such a short time the bottle must have travelled an average of 425 miles per day at almost 18 miles per hour.

In the 1860s, the clipper ship Thermopylae created a new fastest time from London to Australia of 63 days.

Even a modern day luxury cruise to New Zealand can take up to 40 days, including a short cut travelling through the Panama or Suez canals - so the fact the bottle arrived in Whangamata in little more than six weeks is mysterious.

Claire Matthews of the Macduff Marine Aquarium, which is situated just a few miles from where Keely threw her bottle into the sea, said New Zealand was about the last place she would think the bottle could or would have ended up.

"This bottle should really have become stuck in the Atlantic. I can't understand how it would have got off track like this and ended up in New Zealand."

"I can't see how it got to New Zealand. Did somebody maybe pick it up and fly it to New Zealand? It is a bit of a mystery," admits Pearl Reid, Keely's grandmother. Keely is not so surprised. Three years ago she dropped another bottle with a message into the sea at Aberdour and, two years later, it was recovered by a swimmer off the Dutch coast.

"It is brilliant, this bottle travelled farther than I ever have," said Keely.

However experts in ocean currents at the Fisheries Research Station laboratories in Aberdeen are under no doubt there must have been human intervention.

"As a scientist I would usually hedge my bets and leave room for some possibility but there is absolutely no way the bottle could have made it to New Zealand on its own, it must have been picked up by somebody," said Dr Bill Turrell.

"There is no way it could have been picked up by some freak weather system - things just don't cross the equator. I don't like to shatter the poor girl's imaginings but there is no way it could happen."