A 25-year-old man has died while taking part in an organised off-road trail ride in Manawatu.

Police were called to the scene in Waituna West, near Fielding, just after 1pm on Sunday.

A spokesman said he was an experienced and well equipped rider.

The event was a fundraiser for Waituna West School and was being held on a property off Tapuae Rd.

School principal Glen Richardson said the death was a tragedy.

"It's been a pretty tough weekend for everyone concerned."

He said the school board of trustees would be meeting tonight to clarify exactly what happened.

"We are absolutely devastated.

"Unfortunately that's the nature of the sport, there's always risk, even when you do your best to nullify it."

The main trail event takes place in the morning and is about 50km long.

There is also a 30km loop ride in the afternoon.

The matter has been referred to the coroner and WorkSafe has been notified.