The poll by the Library Association has found that at least 234 of librarians will lose their jobs and at least 42 branch libraries will be closed in the next financial year.
Half of the library authorities questioned are expecting cuts to their book-buying funds, many by more than one-fifth. Opening hours of many libraries are also due to be shortened.
The information comes from senior librarians across the country, who oppose the cuts, which result from a harsh budget settlement by central government on the local authorities.
Of the 60 out of 73 library authorities questioned, 41 are expecting cuts of up to 5 per cent of their total budget. Ten expect cuts of up to 10 per cent and three expect cuts above that.
Twelve authorities are planning to close at least 42 branch libraries over the next two years. Cambridgeshire is to close 10 out of 53, Lewisham at least two, and three others privately admit they each expect to close at least five libraries by 1997.
Twenty-nine authorities plan to make at least 234 librarians redundant out of the total 3,139. They include Cambridgeshire (35 over two years), Lancashire (19 posts) and Shropshire (10).
The cost-cutting will also affect opening hours. The 12 authorities planning cuts include Merton, which is to slash 30 hours from the aggregate weekly total of libraries in the borough; Shropshire, which is to cut 48 hours; and Lewisham, which will cut at least 64 hours.
Half the authorities questioned are to cut their budget for buying books and material to serve the burgeoning demand for information technology. The worst affected is Somerset, which will not buy any new fiction next year following a 37 per cent cut.
Of the other authorities, Bury is to cut its book fund by 40 per cent, Merton by 28 per cent, Rotherham by 21 per cent, Kingston by 20 per cent, Lewisham by 20 per cent, and Lancashire, Staffordshire and Shropshire by 15 per cent.
Senior librarians who are required by law to provide a "comprehensive and efficient service" are angry that they are being forced to cut into the bone to meet spending targets.
Mike Hosking, head of libraries and heritage for Cambridgeshire, said: "It's appalling. The next three years could prove disastrous for the quality of public library services in this country."
Michael Dolan, county librarian for Lancashire, said: "There's no doubt that the service we're able to deliver will be vitally hurt by these measures. It raises a question as to whether, in some cases, library authorities will satisfy their statutory requirements."