South Africa will step back into the international fold of the fight against HIV on Saturday as the Aids epidemic, which spread almost unchecked under the previous government, unleashes what its senior trade unionist describes as a holocaust.

Barbara Hogan, the new health minister, will use a visit to one of the hardest-hit townships in Johannesburg to announce that the UK, a big health donor, is to resume significant support for the government’s anti-HIV programme with an initial £15m (€18m, $23m).