JOHANNESBURG — A new study on Monday showed increased HIV infection rates among pregnant women living in areas with high migrant labour in South Africa, the country with one of the world's highest caseloads.

Infections in the eastern province of Mpumalanga jumped from 34.7 per cent in 2009 to 36.7 per cent.

Health Minister Aaron Motsoaledi said some of the districts in these areas had rates above the national antenatal HIV prevalence rate of 29.5 per cent.

"In areas where we see new mining operations, news towns, constructions and new people coming in, we expect something like this higher prevalence rate to happen," said Motsoaledi.

"It needs our attention," he added.

The farming and mining provinces of Free State, North West, Limpopo also recorded increases.

The study was conducted in 2011 on some 33,446 women who attended antenatal clinics for the first time.

The semi-arid Namaqua district in the sparsely inhabited region of Northern Cape recorded the lowest prevalence rate at 6.2 percent. However, the country's economic hub, Gauteng province, which includes Johannesburg and the capital Pretoria showed a slight decrease from 30.4 percent in 2010 to 28.7 percent in 2011.

In South Africa six million people currently live with the virus that causes AIDS.

After years of refusing to roll out drugs, the country now runs the world's largest treatment programme, serving 1.3 million people.

Health officials plan to step up awareness campaigns to fight the scourge.