Mr Lees, 46, the campaigns director of Friends of the Earth, disappeared last Saturday after walking into the forest on a filming investigation 15km from Fort Dauphin on the south-eastern coast. Police co-ordinating the search were yesterday flying tracker dogs from the capital, Antananarivo, to Fort Dauphin. A helicopter was also borrowed from a local hospital.
Friends of the Earth, and Mr Lees' family, have offered a reward in Madagascar for information leading to his return. FoE yesterday declined to say how much this was but described it as a "substantial amount in local terms". His girlfriend, Chris Orengo,a geneticist, and a Friends of the Earth researcher, Jonathan Kaplan, who knows the island well, yesterday arrived in Fort Dauphin to join in the search. Accompanying them was a senior British official from the embassy in Antananarivo, the
capital, who was acting as liaison with local police and village headmen, who have been co-ordinating the search. Staff from the Worldwide Fund for Nature, which has offices in the capital and Fort Dauphin, were also helping in the search.
The embassy said it feared Mr Lees, campaigns director of Friends of the Earth, had had an accident. Villagers in the area were considered peaceful and the forest had no wild animals large enough to attack him.
Charles Secrett, director of Friends of the Earth, said he was growing increasingly worried. "The longer it goes on, the less likely it is that everything is going to turn out well," he said.
The area of forest in which Mr Lees disappeared is remote, inaccessible and so thick that rescuers might not hear somone's cries for help even if they were only 30 or 40 yards away. Colleagues believe Mr Lees may have hurt himself and lost his way or become disorientated.
He had driven out to the forest from his hotel in Fort Dauphin in a four-wheel vehicles with a driver and was due to fly back to London on Sunday. Mr Lees was apparently attempting to get some final video footage before returning. His driver raised the alarm after night had fallen and Mr Lees failed to return.
Mr Lees had a bottle of water on him but no food or survival equipment. He would probably be able to survive for several days but early hopes that he might have been able to find his own way through the relatively narrow strip of coastal forest to the beach, using a mountain range to the north as an orientation point, have been dashed. From the beach it would have been a fairly simple walk to Fort Dauphin.
Madagascar has suffered badly from deforestation in the last decade and the area Mr Lees was researching was threatened by logging, mining and an influx of new settlers. However, FoE would not comment on claims that he was filming for an undercover investigation.
"All we are prepared to say is that Andrew was down there on a tourist visa and was looking at the forest in the area. As a botanist he has a personal interest in the subject," a spokesman said. Mr Lees has a degree in botany from the University of Walesat Cardiff.
Mr Secrett said: "We have no information or evidence which suggests that anything violent or nefarious has been done or that Andrew was under any sort of threat."