Oamaru police yesterday made a public appeal for information following the incident, which happened at 2.45am yesterday.
Detective Sergeant Dan Keno said the offenders had entered the man's bedroom and held him down in his bed.
A number of items valuable to the man were taken.
Inquiries were at an early stage and police were yesterday not in a position to reveal details about the items taken.
''Clearly, for the elderly victim, this is very distressing and upsetting.
''He is currently being supported by Victim Support and we are facilitating as much support for him as possible. However, he's doing very well considering these events.''
A scene examination was under way, Det Sgt Keno said.
''Targeting elderly people in our community is despicable and police will be doing their utmost to locate those responsible and hold them to account.''
Age Concern Waitaki co-ordinator Wayne Stringer said it was ''just abhorrent'' to think an elderly man was the victim of such a crime.
''The people who would do that are just animals.''
Although the Waitaki District Council had recently increased security at its community housing units, elderly people in the town had expressed concerns about safety, he said.
''We are also trying to get round as many elderly people as possible to reassure them that they shouldn't have to live in fear and usually Oamaru is not like that.''
Elderly Oamaru residents yesterday said they were on guard.
Barbara Doran (75) said the situation was becoming ''darn scary''.
''It just leaves you unsettled. It's up to each individual to make sure they lock doors and windows, but even then there's still the fear ... it seems to be the elderly who are targeted, because they [intruders] don't think they will stick up for themselves.''
One 77-year-old woman, who declined to be named, said the incident was ''awful'' and added people needed to be more vigilant and ensure doors and windows were kept locked.
Anyone who had information that might assist police should contact Oamaru police on 433-1400, or provide information anonymously via Crimestoppers on 0800 555 111, Det Sgt Keno said.