The brother of The Block NZ contestants Pete and Andy Walker is missing in Manawatu.
More than 30 police and rescue staff are searching farmland in the wider Apiti area for 25-year-old Stephen Walker.
Four teams made up of staff from Palmerston North, Whanganui, and Levin, along with two search and rescue dogs are involved in the search with another three teams are expected to join them today.
Walker was last seen at his home near Bulls at 8.30pm on Wednesday.
As contestants on TV3's The Block NZ show last year, Stephen Walker's farming brothers Pete and Andy amassed a huge fan base and won the People's Choice Award at the end of the season.
They have since appeared in Hirepool television advertisements.
The Walker family would not be making any statement to the media about the search, Sergeant Andy Brooke, officer in charge of the search, said.
Police were concerned for Stephen Walker's welfare and urged anyone that may have seen him to make contact, he said.
A blue Suzuki farm bike Stephen Walker was believed to be riding was found on Makoura Rd near the intersection of Pohangina Rd in Apiti, north of Palmerston North - the motorbike is a Suzuki TF125.
Police are interested in anyone who had seen a bike matching this description between Bulls and Makoura Road, possibly being ridden by someone without a motorcycle helmet, between the hours of 8.30pm on May 14 and 7.30am on May 15.
"Today we are researching and expanding our search area with the goal of finding Stephen or any signs of where he may be," Brooke said.
Walker is 182cm tall, of medium build with short brown hair and was last seen wearing a green Swanndri, a green hoody, track pants and gumboots.
Anyone with information can contact the Palmerston North police on 06 351 3600 or call Crimestoppers anonymously on 0800 555 111.
- Manawatu Standard
Resource consent being denied for the Basin flyover is:Related story: Board of inquiry says 'NO' to Basin flyover