The Democratic Alliance's spokesperson on defence and military veterans, David Maynier, said in a statement on Tuesday that the international relations minister's demand that the UK government take "strong action" against those who allegedly spied on South African delegates at the 2009 London G20 summit.
He said action was unlikely as the UK's Government Communications Headquarters (GCHQ) has a very broad legislative mandate and that the operation probably took place within the framework of Britain's law.
"If the GCHQ was able to penetrate the Department of International Relations and Cooperation [Dirco]'s computer networks and help themselves to briefing documents, then one must wonder what else they managed to get their hands on," the DA said. "The fact is that Dirco has literally been caught with their electronic pants down."
Minister of International Relations and Cooperation Maite Nkoane-Mashabane called on the British government to investigate the matter fully with a view to taking strong action.
The DA says it will ask Cecil Burgess, chairperson of the joint standing committee on intelligence to investigate this matter as soon as possible.
Edward Snowden leaked documents to the UK Guardian in early June detailing how the GCHQ spied on foreign politicians and officials who took part in two G20 meetings, including South Africa's international relations department.
According to the Guardian, the UK intelligence agency hoped to find out everything it could about the negotiating position of South Africa's 2005 government, then under Thabo Mbeki.
Although the spying did not involve any suspected nefarious activities by South Africa's diplomats, the GCHQ's interest revolved around South Africa's position as a swing vote on issues of global economics and finance.
The agency spied on South African foreign ministry's normal work, acquiring "retrieved document, including briefings for South African delegates to G20 and G8 meetings".
Phone lines used by South Africa's high commission in London were "investigated" and passwords were used by the "computer network exploitation" (CNE) team were used to hack into the online accounts of South African diplomats.
These passwords were acquired by digging up old phone numbers and email addresses of the head of the cryptology department in Pretoria.
According to the Guardian, the CNE team faced difficulty at first in acquiring information as the South African foreign ministry had recently upgraded its networks.
However, the CNE team rapidly acquired passwords to the new system.
International relations and cooperation department spokesperson Clayson Monyela said on Monday the government noted with concern the reports published by the Guardian.
"We do not yet have the full benefit of details reported on, but in principle we would condemn the abuse of privacy and basic human rights particularly if it emanates from those who claim to be democrats," he said.
"We have solid, strong and cordial relations with the United Kingdom and would call on their government to investigate this matter fully with a view to take strong and visible action against any perpetrators."