A coalition of leading medics and key establishment figures have criticised the emergence of "creeping charges" in the NHS.

In a letter to the Independent, the group called for a review of existing NHS levies such as prescription charges and opticians' fees, which they said discriminated against the poor and sufferers of long term illness.

"NHS charges have developed with no clear explanation of why they exist," the coalition wrote.

"The result is a complex, haphazard system, riddled with unfairness and inconsistencies that compound existing health inequalities and penalise the poor."

The group argued that the antiquated and "incoherent" system of NHS charging is now in urgent need of review.

Prescription charges were first introduced in 1952, and were abolished 13 years later.

Subsequently, charges were reintroduced in 1968 and exemptions from charging were established on the grounds of youth, age, income, and for sufferers with long term medical conditions.

But the coalition, which is working with the National Consumer Council, suggested that a fundamental review of these exemptions must take place as illnesses such as cancer, asthma, Parkinson's Disease, multiple sclerosis, cystic fibrosis and some mental health problems are currently excluded from the exemptions to the charges.

The group also argued that many poor families do not understand schemes to exempt them from such charges and often end up going without medication altogether.

And the group concluded that "people on incomes only just above the threshold are doubly disadvantaged".

Both the Scottish parliament and the Welsh assembly have begun the process of reviewing charges, increasing the pressure for England to follow suit.

And the coalition says the time has come for the issue to "command sufficient attention from politicians".

"A fundamental review of the charging system must start with a fundamental question: What is the purpose of charges in a tax-funded NHS that is based on clinical need rather than the ability to pay?"