Sydney - An Australian exploring drains is lucky to be alive after spending three cold mid-winter days below the streets of Melbourne, officials said Saturday.

"He must have gained access via an open drain in the vicinity somewhere and tunnelled down to where we found him," Fire Brigade spokesman Damien Burke said.

The man, in his early 20s, was rescued when passers-by heard his cries. Firefighters used crowbars to pry open a drain cover and free him.

He suffered only cuts and bruises and is expected to be released from hospital soon. (dpa)