The doctor who triggered the MMR vaccine scare has said he had little experience of research on children and was unfamiliar with the ethical guidelines surrounding their treatment.

Andrew Wakefield, whose 1998 paper linking MMR with autism led to a collapse in vaccination levels, said he was not aware of detailed guidance on the subject published by the British Paediatric Association and had relied on colleagues who did.

Dr Wakefield is accused, with two colleagues, of misconduct in relation to his treatment of 12 children involved in the original study. If found guilty, they face being struck off. All three doctors deny the charges.

Dr Wakefield, who has said he has no paediatric qualifications, was cross-examined by GMC lawyers yesterday. He was asked by Sally Smith, QC, how he had "boned up" on the ethical principles involved in research on children. The doctor replied that he had had extensive discussions with colleagues who were "experts in the field" including his co-defendants, Professors John Walker-Smith and Simon Murch.

Ms Smith asked: "If you hadn't read the basic principles, Dr Wakefield, how could you understand what you could or could not do without reference to the particular principles?"

He said: "The answer is very simple. One relies on the input of those who are very conversant."

The hearing continues.