The US did not know about talks on the reportedly imminent release of a South African hostage who died in a US raid on al-Qaeda fighters in Yemen, the US ambassador to South Africa has said.

Pierre Korkie and Luke Somers, an American photojournalist, were killed in the southern Shabwa province on Saturday during a US-led attempt to rescue Somers.

Imtiaz Sooliman, founder of Gift of the Givers, a South African Islamic humanitarian group that had been acting on behalf of Korkie's family, has said that Korkie was supposed to be released on Sunday under a deal struck with AQAP.

Patrick Gaspard told the Associated Press news agency on Monday the US was "just completely unaware of those developments and had to act hastily".

The US decided to carry out the raid because Somers' captors had threatened to kill him, Gaspard said.

He said the US was "unaware of ongoing negotiations that had any resolution'' between Al-Qaeda in the Arabian Peninsular (AQAP), and Gift of the Givers.

A separate statement released by the US embassy in Pretoria said "at no time was it apparent that Pierre Korkie was being held in the same space as the American photojournalist Luke Somers".

Ambassador's remarks

Gaspard said the US had not been informed and that it was "not altogether clear" to him that the South African government was even aware of the talks.

He cited comments by Sooliman that there were no guarantees that the negotiated release of Korkie would have proceeded smoothly.

However, Gaspard conceded that the talks seemed to have made progress, saying: "It does appear that they were pretty far down the track.''

Korkie's wife, Yolandi, was initially also held captive with her husband until January 2014, when she was released under a similar deal negotiated by the Gift of the Givers. 

The South African government issued a statement on Monday expressing their sadness over the death of Korkie.

The statement said Yolandi's release had come after an "intervention by the South African government and the NGO, Gift of the Givers, together with the Yemeni government and other role players".

News that Korkie's death just a day before his scheduled release exploded on social media in South Africa, with users demanding answers from US representatives in the country.

US President Barack Obama has said he ordered the raid because Somers was believed to be in "imminent danger'' after AQAP released a video that showed Somers and threatened to kill him in three days if the US did not meet the group's unspecified demands.

In an interview with Britain's Times newspaper, Somers' parents said they were angry with the operation and that they had been "kept in the dark" about the operation.

Source: Al Jazeera and agencies