"We will be searching the beach area, along the West Coast Wilderness cycle trail, and scrub surrounding the area," Mr Tinnelly said.
He suggested that Mr Green may have gone for a swim and got into difficulty.
Police area commander Inspector John Canning said all scenarios were being investigated.
"Mr Green came to Greymouth with friends, and for whatever reason those friends headed back to Christchurch on Sunday without him," Mr Canning said.
Beaches north of the Grey River would also be searched, he said.
"If anyone has information about Mr Green and his whereabouts they should contact police immediately we need to know that he is safe."
Acting detective senior sergeant Sarah Ellington, of Christchurch police, said this morning Mr Green's disappearance was being treated as that of a missing person.
"Today our focus is the search along the beach, in an attempt to find something that will help us locate him," she said.