The BBC's Torin Douglas: Libraries to be seen as "street corner universities"

He revealed he had already written to six authorities telling them planned cuts could not go ahead and asked 15 others to review their thoughts.

In a letter to library authorities, he said providing library services, which are used regularly by about 10 million people in England, was one of the duties undertaken by local authorities.

"I take this duty very seriously and shall examine in detail the rationale behind any proposed service reductions and other significant changes, such as service restructuring.

"I am therefore taking immediate steps to investigate the situation in a number of authorities."

Mr Smith described public libraries as "street-corner universities" and insisted they were not a luxury that could be dispensed with.

Areas thought to be threatening library closures include Barnsley, Surrey and the London boroughs of Lambeth, Brent, Haringey, Bexley and Camden.

Some other authorities are believed to be planning to scale-back their library services to save cash.

The culture secretary has written to all 149 English public library authorities, saying: "Recent press speculation has suggested that many local authorities are proposing cuts in their public library services.

"At a time when the government has provided the best local authority financial settlement for seven years, unjustified cuts to library services are simply not acceptable."

Ross Shimmon, chief executive of the Library Association, said: "This is a refreshing commitment by government to developing a high-quality public library service fit for the 21st century.

"We have urged successive ministers to support public libraries in the face of damaging cuts to services. Now, for the first time, Annual Library Plans give the Government the tool to jack libraries higher up the political agenda.