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Mr Bates was last seen on February 11 and a massive search has been under way since then. Dozens of Land Search and Rescue (SAR) volunteers have spent hundreds of hours on the search, which has been mainly to the east of Alexandra, near the Manuherikia River.
There had been no official physical search for Mr Bates last week, but intelligence and planning work had continued, Detective Sergeant Derek Shaw said.
Last weekend LandSAR teams did more physical searching, combing the area around the Manuherikia River, going over previously searched areas in more detail.
A helicopter also did a search of the hills behind the Alexandra clock on the hill, from the confluence of the Manuherikia and Clutha Rivers, as far as the Manorburn Dam.
No new information had been received. Police had grave fears for Mr Bates’ safety and would continue searching until he was found, Det Sgt Shaw said.
He paid tribute to the tenacity and dedication of the LandSAR volunteers.
"They are working in extreme conditions in some very rough country, in both very hot weather recently and rain and mud before that. We’d like to express our thanks for what they are doing."
Det Sgt Shaw said the physical search and intelligence operations would now be further reviewed. More physical searches for Mr Bates were planned mid-week and this weekend.
On Friday police released a photograph from CCTV footage taken outside the Alexandra I-site Visitor Centre on February 12, which they believed could be Mr Bates. Following publication, police established the person was not Mr Bates.