Prince Charles
This is the second time Prince Charles' letters have been published (Reuters)

A second batch of previously secret letters written by Prince Charles to government ministers have been released, detailing concerns over hospital food and alternative medicine.

The 17 so-called 'black spider memos', named because of the Prince of Wales's distinctive handwriting, are correspondences between the heir to the throne and ministers in the then Labour government between 2005 and 2009 on issues such as affordable housing in rural areas and upcoming charity work.

The letters revealed Prince Charles wrote to Yvette Cooper, then minster for housing and planning, to express he was "delighted" that the recently published Eco Towns Prospectus contained elements of the Prince's Foundation's Built Environment scheme and will continue to work together.

He also wrote to Cooper to express his "long standing concern" over affordable housing in the countryside and how businesses should do more to help people with low income find homes in rural areas.

One letter also shows Prince Charles and the then health secretary Alan Johnson had "spoke in detail" about hospital food, with Johnson considering proposals to develop a hub to improve food procurement in the public sector.

The latter also shows the Prince of Wales discussing the benefits of complementary medicine in September 2007.

He wrote: "I cannot bear people suffering unnecessarily when a complementary approach could make a real difference. I have been convinced for many years that we in the United Kingdom need to do more to encourage and facilitate good health, as well as to treat illness, and that there should be more of a 'whole person' approach to the treatment of illness rather than a 'reductionist' focus on the particular ailment."

The memos also included conversations with the secretary of state for international development Douglas Alexander to offer an update about the Millennium Development Goals call to action and letters to then minister for housing and planning, Caroline Flint, to mention the "difficulties in completing heritage-led regeneration projects experienced by the Prince's Regeneration Trust".

The first batch of letters were published in May following a 10-year legal battle between the Guardian and Freedom of Information officials.

Those memos revealed the Prince wrote to the then-Labour government about subjects such as beef farming, the badger cull, the use of military equipment in the Iraq war, and alternative medicines.

Reacting to the publication of the second round of letters, a Clarence House spokesperson said: "The correspondence published by the Government shows the range of The Prince of Wales' concerns and interests for this country and the wider world.

"The letters published by the Government show the Prince of Wales expressing concern about issues that he has raised in public like affordable rural housing, the quality of hospital food, the preservation and regeneration of historic buildings, an integrated approach to healthcare, climate change, and others.

"In all these cases, The Prince of Wales is raising issues of public concern, and trying to find practical ways to address the issues."

David Cameron described the decision to make the letters public as a "disappointing judgement".

He added: "This is about the principle that senior members of the royal family are able to express their views to government confidentially. I think most people would agree this is fair enough."