The government was by Tuesday afternoon still trying to trace all the families of eight South Africans killed in a suicide bomb attack in Kabul, Afghanistan.

"We still have not been able to contact all the families," said international relations spokesperson Nelson Kgwete.

The names of the victims would not be released until all the next-of-kin had been notified.

"It could be today, it could be tonight, it could be tomorrow," said Kgwete.

The department was making efforts to confirm the identities of those killed, and was in possession of the names of the eight South Africans.

Kgwete said the department was also in contact with the aviation company that employed those killed.

The attack occurred around 04:00.

The South African High Commission in Islamabad, Pakistan, was informed on Tuesday morning that eight South Africans had been killed in the attack.

The department expressed its sincere condolences to the families, friends and colleagues of the victims.

Kgwele said the necessary consular assistance would be rendered to the families.

The French news agency Agence France Presse (AFP) reported that a woman bomber carried out the attack which killed 12 people.

The attack was to avenge a US film that has sparked a week of deadly protests across the Muslim world, reported AFP.

The bombing brings to more than 30 the number of people now killed in a violent backlash over a YouTube trailer for the film, "Innocence of Muslims", believed to have been produced by a small group of extremist Christians.

According to AFP, Hezb-i-Islami, the second largest insurgent group in Afghanistan after the Taliban fighting US-led troops and the government for ten years, claimed responsibility for the attack.

"The bombing was in retaliation for the insult to our Prophet," spokesperson Zubair Sidiqi told AFP in a telephone call from an undisclosed location.

According to the BBC, the victims were in a van refuelling at a petrol station close to Kabul International Airport, when the suicide attacker rammed a vehicle into the van.

An eyewitness told the BBC the van refuelled at the same place every day.

The broadcaster reported that Afghan intelligence services believed the attacker had information about the victims and that it was a targeted killing.