Melbourne tennis coach Paul Arber was seen to stop at an ATM, give money to a homeless man and pat a couple's dog before he went missing in Hamilton on New Zealand's North Island on Saturday.

Police confirmed Mr Arber's wallet and keys were found discarded near where he was last seen and now hold grave fears for his safety. Mr Arber - a former Kooyong Tennis Club captain and the 2012 Victorian Jewish Tennis Champion - was last seen about 9pm near a park in an area described as ''dodgy'' by locals.

He was in Hamilton with eight of his charges for a junior tennis tournament, held at courts near where he was last seen alive.

A friend of 28 years, Nathan Hude, watched from across the road as Mr Arber disappeared around a street corner.