By Barnaby Phillips BBC southern Africa correspondent

A South African court has upheld a ruling that the government must make more widely available a drug which reduces the risk of HIV-positive women passing on the virus to their children.

This is another setback for the government, which has argued that the drug, Nevirapine, is expensive to distribute and potentially dangerous.

South Africa, with an estimated one in nine people HIV-positive, has the largest infected population in the world.

South Africa's president believes HIV does not lead to Aids

Aids activists want all pregnant women to have access to the drug, which is thought to reduce by half the risk of passing on the virus to an unborn child.

The high court in Pretoria ruled that state hospitals with the necessary capacity must provide Nevirapine, and that they should not wait for the results of the government's next appeal.

This issue will probably go before South Africa's highest court, the constitutional court, in May.

In the meantime the arguments surrounding Nevirapine are once again on the front pages of South Africa's newspapers.

Tutu call

Aids activists believe that the government's reluctance to use the drug originates from President Thabo Mbeki's unorthodox views on the disease.

President Mbeki has argued that the extent of the Aids pandemic is exaggerated and has questioned the link between Aids and HIV.

On Monday, the distinguished former archbishop of Capetown - Desmond Tutu - added his voice to those calling on the government to respect the court's decision and act with greater urgency.

He said South Africans must fight Aids with the same passion that they fought apartheid.