The report, by economist Christopher Smallwood, will say patients with conditions such as back pain and stress can benefit from some of the therapies.
However, there is a shortage of treatments such as acupuncture and osteopathy in poor areas, it will say.
The report is not thought to say wider use would bring huge NHS savings.
Deprived areas
The report is an overview of available
evidence about complementary and alternative
therapies.
Millions of people use complementary
therapies in the UK, and demand is growing.
About half of GPs now provide some kind of
access to such treatments.
Some "mainstream" therapies, such as osteopathy, chiropracty and acupuncture, could have a larger role in NHS care, the report will say.
But it will say that the benefits of
homeopathy - a therapy which works on the
principle of treating like with like - are
more questionable.
'Not up to scratch'
Prince Charles, an enthusiast for
alternative medicine, commissioned the
independent economist to compile the report
nine months ago, but has had no involvement
in its preparation since then.
The report includes the views of health professionals, and case studies where treatments have been used.
The prince has not yet seen the finished version.
But his involvement has led some experts to question whether the study was biased in favour of these treatments.
Edzard Ernst, professor of complementary medicine at the University of Exeter's Peninsula Medical School told BBC Radio 4's Today programme he had concerns over the report.
Professor Ernst was interviewed during research for the report, but asked for his contribution to be withdrawn.
He said a draft version which he had seen "wasn't really up to scratch".
'Money well spent'
Professor Ernst added: "I am, of course, in
favour of using complementary medicine but
it needs to be backed up by good science and
that wasn't good science.
"It looked to me as though the conclusions were written before the data were put in.
"Complementary medicine has a lot to offer but it would be really very counter-productive if we just uncritically integrate things that aren't backed up by evidence."
Professor Ernst added that five existing reports on the cost-effectiveness of complementary medicine had indicated it was "an add-on cost, not a cost saving".
But Mr Smallwood said the criticism of the report was unfair because Professor Ernst had not seen the final version.
He also denied he had any "axe to grind" in terms of manipulating the data to fit certain conclusions.
Mr Smallwood said: "Overall, we are not saying there would be sweeping savings to the NHS budget.
"What we are saying, however, is that many of these treatments are cost-effective.
"That is to say, that if you spend money on them, the improvement in healthcare which results means that that money is well spent."
