SCOTTISH business leaders have called for the remit of the Scottish Investment Bank (SIB) to be widened, to help far more companies than those export-led, high-growth businesses that it is targeting as the economic situation deteriorates.  They are concerned that the flagship Scottish Government initiative to help small and medium sized enterprises raise cash is doing nothing for the vast majority of firms during a challenging period for businesses.  The slowdown in the economy has added fresh urgency to complaints that SMEs are being hit hardest by the shortage of bank funding resulting from lenders efforts to rebuild their balance sheets.  However, the SIB is concentrating on a narrow band of firms in sectors such as life sciences and renewable energy that are reckoned to be capable of achieving rapid growth.  Critics complain that established businesses in other sectors are excluded, although these provide the bulk of private sector jobs in Scotland.  Liz Cameron, chief executive of Scottish Chambers of Commerce said:  We need to stop artificial barriers or restrictions being placed as to which sectors can apply,  said.  Construction, infrastructure developments, retailing, tourism, general business operations   they all collectively employ millions of individuals and need to be sustained to enable them to work through the economic conditions. They cannot do this if they do not have cash.  She said the SIB should develop a new fund to provide short-term working capital for firms with private sector support.  Colin Borland, head of external affairs for the Federation of Small Businesses in Scotland, said:  They (the SIB) are of limited relevance to our members.  He added:  These times are fairly unusual. You can t take it as read that the business base will always exist.  We should be looking at ways of expanding and sup