More than 200 people are searching for an Air New Zealand pilot who went missing on a tramp in Hong Kong three days ago.
First Officer Stephen John Morrissey was last seen on Wednesday while walking with Captain Mark Apperley on the Wilson trail in Hong Kong's New Territories on a day off.
Air NZ deputy chief executive Norm Thompson said a core team searched overnight, and more than 200 personnel were involved today.
"The search has been expanded to take in a much larger geographical area, including more of the track and a wider area either side of it," Mr Thompson said.
"The Hong Kong police have told us this morning that, if necessary, the size and scale of the search operation will continue all day tomorrow as well."
Family members and Air NZ staff in Hong Kong were drawing strength from the dedication of the police and remained hopeful Mr Morrissey would be found.
There had been no suggestion of foul play.
Mr Morrissey and Mr Apperley became separated when the latter took a rest, and Mr Morrissey failed to arrive at the agreed meeting point, about 1km away at the end of the track.
After waiting for an hour, Mr Apperley returned to their hotel to raise the alarm.
The area where Mr Morrissey had gone missing was fairly easy terrain, and the pair had water, a backpack and some other provisions.
Mr Morrissey was fit, had tramped for years and was familiar with survival techniques from his earlier career in the air force.
Hospitals, hotels and other locations throughout Hong Kong have been checked in the search.
Mr Morrissey's two sisters and sister-in-law have travelled to Hong Kong to help with the investigation.