Three dozen baby elephants at the centre of a controversy over the sale of wildlife to Chinese zoos have left Zimbabwe after they were loaded secretly onto a cargo flight, the Telegraph has learnt.

Thirty-two of 37 young elephants were removed from a holding facility in Hwange National Park in the early hours of Thursday morning and loaded onto a Saudia Cargo jet at Victoria Falls airport in the afternoon, sources close to transfer said.

Five of the elephants were rejected, apparently for health reasons.

The Zimbabwe National Society for the Protection of Animals, the national animal welfare agency, confirmed the reports but said its inspectors had been denied access to the elephants to check on their welfare.

"Inspectors on the ground have confirmed that an unknown number of elephants were loaded at Victoria Falls airport. The destination and of which is unknown. The buyers are unknown and the condition of the animals are unknown," a source close to the society said.

"The airport was on lock down. There was no transparency and it was very secretive," the source said.