Among the movies that have been awarded this support are Sunshine on Leith, The Railway Man, Under the Skin and Starred Up, each of which received £300,000.
But the letter from Independent Producers Scotland notes that other countries invest far more in their screen industry, including Denmark, which allocates £52m, Sweden (£36m), and Northern Ireland (£13m). It raised concerns that filmmakers in Scotland cannot make a "decent living" from the industry.
It states: "In other countries, film producers with the right support mechanisms are able to make a living out of film.
"In Scotland, however, the vast majority of film production companies and producers are in financial crisis. Lack of funds and support is killing the industry."
Creative Scotland, which is currently carrying out a major review of the film industry in Scotland to be published in January 2014, said the points made were of "significant value" and discussions would take place with the Scottish Government on the concerns raised.
About 22 feature films are shot in whole or in part each year in Scotland and £20-25 million is spent by production companies shooting on location around the country.
British Film Institute figures show there were 150 film production companies in Scotland in 2012 - 2.9% of the UK total. Another 75 film companies based north of the Border were working in areas including post-production, film distribution and film exhibition. More than half - 55.3% - of film companies were based in London.