Building unions have slapped a construction ban on the site of a historic Carlton pub demolished illegally on the weekend.

And they say the company that purchased the Corkman Irish Pub for $4.76 million last year should be forced to surrender the land to Melbourne City Council.

The 159-year-old pub, formerly known as the Carlton Inn, was knocked down without a demolition or planning permit – sparking five separate government investigations into what laws may have been broken.

The pub, which had a heritage overlay, was already at the centre of a police arson investigation over a fire that broke out there the week before.