OXFORD University has defended itself amid claims that its research is funded by companies that support "sustainable trophy hunting".

Cecil the lion, shot in Zimbabwe last month by an American dentist, was being studied by Oxford University's Wildlife Conservation Research Unit (WildCRU).

But it has emerged that the unit's research is partially funded by Panthera - whose website describes the organisation as "leaders in wild cat conservation" - and the Dallas Safari Club, which support sustainable trophy hunting.

Prof David Macdonald, founder of WildCRU, said there was not a conflict of interest and said the unit was "not an advocacy organisation".

He said: "We simply do our work. There is no risk of any donor affecting our results.

"We report our results regardless of whether they state any particular point of view or not."

Prof Macdonald said that it was up to "wider society" to decide on hunting laws, but that WildCRU was simply an "evidence-based organisation".

Dr Luke Hunter, executive vice president of Panthera, said that while "far too many lions are being shot for sport", hunting can "benefit lions".

Dr Hunter posted a blog earlier this year saying: "In Africa, sport hunting is the main revenue earner for huge tracts of wilderness outside national parks and reserves.

"The presence of hunting provides African governments with the economic argument to leave safari blocks as wilderness.

"Without it, cattle and crops - and the almost complete loss of wildlife they bring - start looking pretty attractive."

A spokeswoman for the Dallas Safari Club said it "absolutely" supports sustainable trophy hunting, but not comment further.

Chris Macsween, a trustee of the conservation charity LionAid, said: "LionAid does not believe that there is any such thing as 'sustainable trophy hunting' of vulnerable and endangered species.

"This is equivalent to a tobacco company accepting research from their stable of scientists to say that smoking is not damaging to health."

The news came as donations for Cecil the Lion reached more than £550,000 and more funding was pledged by Ty Warner who founded Beanie Babies.

A new Cecil the Lion Beanie Baby has been created by Mr Warner, who has pledged 100 per cent of the profits from the sales to WildCRU.

The move was welcomed by Prof Macdonald, who said donations would be used to expand the research project and enable them to employ more local people.

He added: "We will devote ourselves to working for the conservation of lions in Hwange and, with this marvellous support, the surrounding landscapes in adjoining countries.

"I believe that the worldwide engagement with Cecil's story transcends the tragic fate of one lion, and sends a signal that people care about conservation and want it to be reflected in how humanity lives alongside nature in the 21st Century."