A British couple feared kidnapped by Islamic State extremists in South Africa had been filming with a BBC Gardeners’ World presenter shortly before they vanished.

Horticulturists Rodney Saunders, 73, and his wife, Rachel, 64, went missing two weeks ago.

Police have arrested a man and a woman who have links to Isis fanatics on suspicion of kidnapping and possibly killing the couple in the remote foothills of the Drakensberg mountains on February 12.

Rachel Saunders and her husband Rod. Police said around £20,000 had been withdrawn from their bank account

The couple emigrated in the 1970s and lived in Cape Town. They were searching for a rare plant in mountains outside the city when they disappeared

The couple, who emigrated in the 1970s and lived in Cape Town, had been in the desolate area searching for a rare gladiolus plant with Gardeners’ World presenter Nick Bailey and a BBC camera crew.

On February 8, the broadcaster posted a ‘selfie’ with the pair – believed to be the last picture of them alive – with the caption: ‘These guys know their South African native plants.’

Police sources said around £20,000 has been withdrawn from their bank account since they vanished. Officers found their Land Cruiser jeep covered in blood 150 miles away from their last-known location.

South African special forces police have arrested Sayfdeen Aslam Del Vecchio, 38, and Fatima Patel, 27, who are believed to have had Isis recruiting material at their ramshackle hideout in Ngoye, near Mtunzini.

The Foreign Office has updated its website to warn Britons of ‘likely’ attacks by Islamists in South Africa.