A man aged in his 60s has been flown to Palmerston North Hospital with serious injuries after being hit by the bucket of a digger.

Emergency services were alerted to the accident in the Manawatu Gorge at about 11.30am, an ambulance spokesman said.

"We understand it was somebody working on a railway line."

"He was winched out by the Palmerston North [Rescue] Helicopter and transported to Palmerston North Hospital in a serious condition," the spokesman said.