1. A method for automatically locating tables in documents, the method comprising the steps of: defining a plurality of tiles for a document; determining a horizontal profile and a vertical profile for each of the plurality of tiles; detecting lines by means of the horizontal and vertical profiles; determining at least one rectangle from the lines; accepting from the at least one rectangle a rectangle as a table of a document; determining a location of a line by means of a gradient of one of the horizontal profiles and the vertical profiles; selecting persistent lines from the located lines; determining at least one rectangle from said persistent lines; and for each determined rectangle, applying heuristics in order to accept or reject the rectangle as a table of the document; wherein the step of selecting lines that are persistent comprises the steps of determining a tolerance parameter and considering lines in consecutive tiles, which lines are not separated by more pixels than the value of the tolerance parameter as the same persistent line.