Neither food nor food supplements are alternatives to drug therapy in treating people with HIV/AIDS, South Africa's top scientific advisory panel said on Tuesday, amid a controversy over the nation's AIDS policies.

The report by the Academy of Science of South Africa was issued as President Thabo Mbeki faced new criticism over support for his health minister, who promotes nutritional treatment for AIDS, and the sacking of a deputy minister who backed drug treatments.

The inter-disciplinary scientific panel, which advises the government on health policies, began studying nutritional influences on the human immune system in October 2005, focusing on the virus that causes AIDS and tuberculosis (TB).

"The panel has concluded that no food, no component made from food, and no food supplement has been identified in any credible study as an effective alternative to appropriate medication," said Prof Barry Mendelow, chairman of a 15-member panel from the Academy of Science of South Africa (ASSAf).

Mendelow told Reuters the panel found while nutritional intervention is "a valuable supportive measure", the primary treatment is anti-retrovirals and anti-TB drug therapy.

"It's not a question of one or the other," he added.

South Africa has one of the world's highest HIV infection rate with an estimated 12 percent of the country's 47 million population infected with the deadly virus.

Besides a struggling health-care system characterised by a lack of doctors and nurses, many of whom have left the country for better pay abroad, the fight against AIDS has been hampered by conflicting messages from senior government officials.

Mbeki sacked Deputy Health Minister Nozizwe Madlala-Routledge this month for insubordination, sparking an outcry from AIDS activists who strongly backed her policies and critics who say she was fired for political reasons.

Madlala-Routledge had clashed with Health Minister Manto Tshabalala-Msimang, dubbed "Dr Beetroot", who had horrified AIDS activists with her advocacy of garlic, lemon and African potatoes over conventional anti-retroviral drugs.