SCOTLAND'S medium-sized businesses are the key to future growth, according to business advisers BDO.

The firm says statistics from the Scottish government show widely disparate performance levels depending on size of business and corporate structure. Total turnover per employee for all of Scotland's 343,345 businesses is £109,468. For very large firms - those with 250 and more employees - the figure is £125,909, for businesses with fewer than 49 employees the figure falls to £73,215, but it rises substantially to £137,766 among the medium-sized enterprises (50 to 249 employees). Martin Gill, lead partner with BDO in Scotland, commented: "What this shows is that mid-market businesses - often the unsung heroes of our economy - are the most productive segment of Scotland's private sector."