Health Minister Zweli Mkhize expressed his concern about the global shortage of test kits for Covid-19, saying it will lead to a backlog.
Briefing the National Council of Provinces on Tuesday, he said in the previous 24 hours, 12 900 tests were conducted for the dreaded virus. The previous day there were about 20 000 tests.
The drop was due to the worldwide shortage of test kits, Mkhize added.
A backlog could mean doctors will have to make clinical diagnoses.
He said the backlog was not due to a lack of capacity, but a shortage of test kits.
Western Cape MPL and chairperson of the provincial legislature's ad hoc committee on Covid-19 Mireille Wenger said the backlog in the province was 18 000.
"If we can't measure, we can't manage," she added.
By 24 May, 596 777 tests were conducted.
On Monday, 12 922 tests were conducted and of those, 2 999 (23%) were from community screenings and testing and 5 473 (42%) were in the public sector.
Gauteng has performed the highest number of tests - 37.2% with a positivity rate of 2.4% - whereas the Western Cape has performed 27.9% with a positivity rate of 18.4%.
Mkhize said the high number of infections in the Western Cape - the province with the highest number of infections - could not be ascribed to a higher rate of testing and those that hold that opinion were ill-informed.
He added the past two weeks saw 45% of the total positive tests. This past week saw 25%, with the Western Cape leading the way, followed by Gauteng.
Mkhize expressed his concern about the level of hospitalisation in the Western Cape, which dwarfs the figures in the rest of the country.