A survival expert has teamed up with a missing zoologist's friend to help trace him in the depths of West Africa.

Christian Velten was last heard from in March following the route of the River Niger.

The 28-year-old from Brighton was attempting to recreate an expedition by 18th Century explorer Mungo Park.

Christian made his last call to parents Pauline and Timothy, who live in Burwash, from Kita in Mali. He was then spotted 300km away in the capital Bamako in early April but failed to return home as planned in July.

His friend Sam Rice-Edwards has now flown to Mali with a military tracker to find out what happened to him. Another friend, Vicky Paterson, is co-ordinating publicity.

Vicky said: "The team intend to meet all the relevant officials in Bamako over the next few days and confirm how best to work with the local police.

"They will then verify the last sightings, make inquiries around the city, for example in hostels, before hoping to pick up Chris' trail on the other side of the capital en-route to the river.

"They will be accompanied by a driver and a guide."

She said Sam's escort was being hired by the Velten family initially for one month.

Vicky added: "He has an army background and is being used for his skills in organising information and his proven ability to orientate and survive challenging terrain."

Christian's route would have taken him through Niger and Nigeria.

Dangers on the way could include hippos, lions and bandits.