The doctor who sparked the MMR controversy paid children #5 to take their blood samples at his son’s birthday party, a disciplinary panel heard today.

Dr Andrew Wakefield is accused of showing "callous disregard for the distress and pain" he knew or ought to have known the children might suffer as a result of his actions.

He is also accused of abusing his position of trust and bringing the medical profession into disrepute.

Dr Wakefield and Professors John Walker-Smith and Simon Murch are appearing before the General Medical Council (GMC) Fitness to Practise Panel in central London to hear disciplinary charges against them.

They are accused of serious professional misconduct and face being struck off in a case expected to last several months.

The trio published a paper in The Lancet medical journal in February 1998 suggesting there could be a link between the triple jab, bowel disease and autism.

It led to falling numbers of parents immunising their children and a row over whether the then prime minister, Tony Blair, had vaccinated his son, Leo.

Before the hearing, parents gathered to show their support for Dr Wakefield - who now works in the US - by holding placards, clapping and cheering as he walked in.

Some signs read "We’re with Wakefield", while others said "Wakefield Cares".

He and his wife, Carmel, posed for pictures while a few parents chanted "There’s only one Andrew Wakefield" and one shouted "It’s a witch hunt."

One supporter was Sue Gilbert, from Bath, whose 16-year-old son, Adam, has Asperger’s syndrome.

She said: "My son had the MMR job at 14 months and had a terrible reaction to it.

"About 10 or 11 days later he came out in a measles rash, he was very poorly. Prior to the MMR he was a totally normal child. We took him to see Andy Wakefield when he was eight. He was the only doctor who listened to us, who took us seriously.

"Adam was investigated and found to have an inflammatory bowel condition. Andy was willing to treat him whereas our GP was not."

The allegations against the doctors relate to investigations for their study on 12 youngsters with bowel disorders carried out between 1996 and 1998.

At the time, all three doctors were employed at the Royal Free Hospital’s medical school in London, with honorary clinical contracts at the Royal Free Hospital.

They are accused of performing colonoscopies and lumbar punctures on children without proper approval and "contrary" to the children’s clinical interests.

Dr Wakefield and Prof Walker-Smith are also accused of acting "dishonestly and irresponsibly" in failing to disclose in the Lancet paper the method by which they recruited patients for inclusion in the study.

It is also alleged that a drug was administered to one child for experimental reasons.

One of the key allegations against Dr Wakefield is that he was being paid at the time for advising solicitors on legal action by parents who believed their children had been harmed by MMR.

Another charge is that he ordered investigations "without the requisite paediatric qualifications".

All three doctors are accused of conducting the study on a basis which was not approved by the hospital’s ethics committee.

One example is that some of the children may not have qualified for the study on the basis of their behavioural symptoms.

Several Royal Colleges and faculties signed a statement ahead of the hearing, saying there was no evidence of a link between MMR and autism.

The statement said: "The undersigned believe that the MMR triple vaccine protects the health of children.

"A large body of scientific evidence shows no link between the vaccine and autism."

Among signatories are the Royal College of Paediatrics and Child Health, the Royal College of General Practitioners, the Royal College of Pathologists, the Royal College of Physicians, the Royal Society of Medicine, Great Ormond Street Hospital for Children NHS Trust, and the UCL Institute of Child Health.

Supporters of Dr Wakefield have collected more than 7,000 signatures in an online petition.