Man found safe after Melbourne unit fire

An elderly man is safe after his unit was razed by fire in Melbourne.

A neighbour raised the alarm when they saw flames through the roof of the Tullamarine unit about 1am on Monday, the Metropolitan Fire Brigade says.

An extensive search of the destroyed unit failed to find the occupant but he has since been located and was not home at the time of the blaze, police say.

It's not yet known what caused the fire - which left a damage bill of up to $300,000 - but it is being treated as suspicious.