More than six million pupils across the country have started writing the annual national assessment exams - and Basic Education Minister Angie Motshekga is "expecting the worst".

The tests are intended to assess whether children's skills, such as literacy and numeracy, and especially analytical skills, are at the appropriate level for their age.

Motshekga, who was at Midrand's Ebony Park Primary School for the start of the tests, said: "I expect the worst, but we need to know the worst so that we can address the weaknesses [in the education system]."

The assessment exams will show how South Africa's school children compare internationally, she said.

"Pupils can learn, but they can also forget. This is not only about knowledge, because people forget facts. It is about skills . interpretive and analytical skills . and are these children at the right levels."

It was expected that about 12million pupils will have to write the assessment exams by June.

Parents will be told how their children performed.

Teachers do not see the exam papers before their pupils write and so cannot prepare them for the questions.

"If there are gaps in their education or skills, we need to know what they are so that we can take action," Motshekga said.

The marking of the exams by teachers has been criticised.

But Basic Education spokesman Hope Mokgatle said steps had been taken to prevent teachers inflating marks.

These included external verification of marking.

Most schools should have reported pupils' results to parents by the end of next month.