A rapid new test for HIV, the virus which causes Aids, has been approved by the American Government's Food and Drug Administration (FDA).

The test, devised by OraSure Technologies, can deliver results in about 20 minutes.

The company says quicker diagnosis could reduce the spread of the disease and help people get treatment earlier.

Quicker information could lead to speedier treatment, it is hoped

But Andrew Pendleton, an anti-Aids campaigner for the Christian Aid organisation, told the BBC that, although easier diagnosis was helpful, the priority in many parts of the world was to be able to provide HIV-sufferers with adequate health information, counselling and treatment.

The US Health and Human Service Secretary, Tommy Thompson, said:

"With this new test, in less than half an hour, (patients) can learn preliminary information about their HIV status, allowing them to get the care they need to slow the progression of their disease and to take precautionary measures to help prevent the spread of this deadly virus."

OraSure has an agreement with Abbott Laboratories to help distribute the HIV test, called OraQuick.

After the announcement, OraSure's shares rose 66 cents to $6.44 on the Nasdaq index.

OraSure says the treatment works by taking a sample of blood from a finger prick and putting it into a developer solution. The OraQuick is then inserted into the solution and gives a result shortly afterwards.

Previously, patients have faced an agonising wait for days as blood samples are sent to laboratories for analysis.

Concern for Africa

Mr Pendleton told the BBC's Newshour programme that the FDA had said the new test would have to be administered in a controlled health service setting.

"That is not something you are going to be able to go into an African village," he said.

He said that about 28 million people in Africa are believed to be infected with HIV and only 30,000 of those are able to afford treatment.

"The problem is vastly outstripping the resources," he said.