Cosatu has condemned the suicide bomb attack that killed eight South Africans in Kabul, Afghanistan.
"The Congress of SA Trade Unions [Cosatu] strongly condemns the murder of eight South Africans and four others in an explosion in the minibus in which they were travelling," it said in a statement on Wednesday.
"We send our condolences to their families and friends on the tragic loss of their loved ones."
Cosatu said there was no justification for the random killing of South Africans and others, whatever the complaint may have been. The motive for the attack was reportedly a film, made in the United States, about the Prophet Mohammed.
"We demand that the perpetrators be brought to justice."
The South Africans were killed around 4am on Tuesday.
Beeld newspaper reported that the victims worked for the Johannesburg company, ACS/Balmoral.
The suicide bomber, thought to be a woman, also died in the attack, as did the Afghan minibus driver, a ground crew member from Kyrgyzstan, and a pedestrian.
The Airline Pilots' Association (ALPA-SA) condemned the killings.
"This is indeed a very dark day in our industry," president of the association Captain Fanie Coetzee said in a statement.
Members of the ALPA-SA were among those killed.
"This abhorrent and senseless tragedy is viewed by the Association as not only a direct threat to civil society and global peace, but a blatant and deliberate attack on innocent civilians."
Coetzee extended the ALPA-SA's condolences to the families of those killed.
The African Christian Democratic Party was also aggrieved by the deaths.
"We strongly condemn the practice of suicide bombing and those responsible for it. There can be no justification for so heartlessly and cruelly taking these and other lives," its chief whip Cheryllyn Dudley said in a statement.
"We are, however, angry that people can be so careless in their actions that they have no regard for the lives of those who may be affected by their brash and inflammatory actions."
The ACDP called on "Media for Christ" to either refute accusations that they were involved in the production of the anti-Islam film, or take responsibility for their actions.