An investigation is underway after the bodies of two elderly men were found inside an inner city house in Sydney.

The men, aged 74 and 83, were found in separate rooms of a “hoarder’s house” in Surry Hills at about 2pm on Thursday.

The 74-year-old was discovered first, before the second body was found upstairs.

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It’s understood there were no visible signs of injury on either body.

Police believe they died at different times within the past month.

A 63-year-old woman who lives at the property has been spoken to by detectives.

7NEWS understands she has cognitive issues and reportedly disclosed the situation to someone else, who then alerted police.

As investigations underway, police are urging anyone with information about the incident to come forward.

It is not being treated as suspicious at this stage.