"It's almost confirmed that the two South Africans are now held by al-Qaeda men," the official told Agence France-Presse on Thursday.
He said the kidnappers had taken the hostages to the rugged mountainous region of Hazm al-Udain, 50 kilometres north-east of Taiz.
"Security forces have tracked them but the results are so far not very encouraging," he said, refusing to elaborate on what he meant by that.
Local tribal sources said armed al-Qaeda militants have been present in Hazm al-Udain during the past few months and had been training in the area every night.
Security officials said last month that gunmen kidnapped the pair on May 27 over a land dispute between a local chief and the authorities.
South African diplomats had headed to Yemen to try to secure their release. No information has been provided since on their progress.
The couple, initially thought to be tourists, were involved in the development of a hotel in the city of Taiz, South Africa's foreign ministry said last month.
One security source in Yemen said they were seized while they were outside a hotel in the eastern part of the city.
The senior security official said on Thursday that the couple worked as teachers in Taiz before they started working five months ago for a local investor, without specifying where they worked. – AFP