Sydney teen missing in Melbourne

A Sydney man missing from his Melbourne holiday apartment was acting strangely and appeared to be delusional the last time his friends saw him.

Rhys Jones, 19, briefly returned to the Hardware Lane unit on Sunday but his friends have told police he appeared to be delusional.

The teen's phone is switched off and he has not been active on social media for several days.

His worried parents have travelled to Melbourne to assist in the search.