A SOUTHAMPTON University expert has been hired to find out if David Blaine is cheating in his bid to survive in a glass box next to the Thames for 44 days.

The illusionist claims to be surviving on nothing other than water during his six-week stint in the box, which has attracted huge crowds to the site next to Tower Bridge.

But Blaine has been dogged by accusations of cheating and reports suggesting he is actually gaining weight while he starves himself.

Conspiracy theories abound, with some suggesting he has secreted glucose tablets somewhere in the box to boost his body while he starves.

Others claim there is something in the water, colourless and tasteless "glucose polymers" which wouldn't show to the naked eye.

In an attempt to put a stop to the gathering whispers once and for all, a Southampton General Hospital starvation expert has been called in to verify Blaine is as good as his word.

Prof Marinos Elia, of the Institute of Human Nutrition at Southampton General Hospital, is recognised as the country's leading nutritionist.

He has the unenviable task of analysing the master magician's urine to check for traces of anything that shouldn't be in the box.

Prof Elia has agreed to be an independent monitor and has been given the power to carry out unannounced spot checks to make sure everything is above board.

Blaine urinates into a funnel, which is connected to a hose leading to a container below the glass box. This is the start of a journey which, for some samples, ends in a Southampton laboratory for analysis.

The initial tests seem to back Blaine's boast that he is as transparent as his cage.

"They are consistent with starvation," reports Prof Elia. "The salt level is very low - ten times lower than you would expect it to be. When the body starves it tries to retain as much salt as possible. The kidneys reabsorb it after filtering the body's liquids."

Salt is particularly important because without it Blaine's brain would start to swell, causing depression and delusions.

Other tests on the urine also support a starvation analysis, leaving Dr Elia in little doubt.

"This is one sample, a snapshot in time. In the end one has to put all the pieces together. But, in my view, this sample is entirely consistent with someone who is starving."