The number is 0800 234 7437 and will be open between 9am and 6pm over the weekend. Outside of these hours a message can be left.
Mr Forlong said police were particularly interested in anyone who may have had their property interfered with, or who had discovered any items missing.
"We're also interested in anyone who may have found anything unusual in the beach area," he says.
"We are still seeking sightings of Alex Fisher and his brother Eric at the start of the week, either together or by themselves."
He added that even if the information did not seem relevant, people should call police to let them make the assessment.
The investigation team, from Auckland, Wellington, New Plymouth and Whanganui, continued to work on the case.