A New Zealand soldier's Gallipoli war medals have been stolen from a package sent to Dunedin from Australia.

Police in Victoria say they are investigating the theft of the medals, which were sent via registered post from a post office in Doveton, Melbourne, on February 4.

The package contained six medals, six miniature medals, a Gallipoli lapel, an RSA badge, a ribbon bar, service records and medal photographs.

However, when the package arrived at the recipient's Dunedin address on February 12, it was discovered the padded post bag had been tampered with.

All of the items, except for the service records and photographs, were missing.

Police say the bag was re-sealed with tape, and it was not known when the medals were removed.

Investigators were told the medals originally belonged to a man who served in Gallipoli with the New Zealand Mounted Rifles Brigade.

He also served in the New Zealand Air Force during World War II and was a founding member of the Wellington Gallipoli Veterans' Association, as well as being a member of the New Zealand War Amputees' Association.

An Australian auction listing for the medals, which were put up for sale in 2011, said the medals belonged to Herbert George Garratt, who was wounded in action in the Dardanelles in August 1915.

He was sent back to England due to leg wound complications which required specialist treatment.