A woman who does not want her seven-year-old son to have radiotherapy treatment following surgery on a brain tumour has renewed her High Court fight.

Sally Roberts, 37, of Brighton, East Sussex, fears radiotherapy will cause her son, Neon, long-term harm. Doctors say Neon might die within months without radiotherapy.

A High Court judge began hearing more evidence about the pros and cons of radiotherapy.

Earlier this week, Mr Justice Bodey ruled that Neon could have further surgery against Ms Roberts' wishes.

Ms Roberts, who comes from New Zealand, wanted a second operation to be delayed until more doctors had been consulted. But specialists said follow-up surgery needed to be carried out urgently. And Mr Justice Bodey said the operation should go ahead.

A doctor treating Neon told the judge that the operation went well.

Ms Roberts has told the court she is not a "bonkers mother". She fears radiotherapy will reduce Neon's intelligence quotient (IQ), shorten his life, put him at risk of having strokes and make him infertile. Ms Roberts has said she would agree to Neon being given chemotherapy because any damage caused could be "overcome".

"The mother remains concerned that radiotherapy is not in Neon's best interests," Ian Peddie QC, for Ms Roberts, told the judge. "We assert that there are doctors who can offer credible alternative treatment to the therapy that is proposed."

Neon's father Ben, who lives in London and is separated from Ms Roberts, has agreed to radiotherapy but is "apprehensive", the court has heard.

A specialist treating Neon has described Ms Roberts' comments as "sensible" and accepted that there could be side-effects to radiotherapy. But he said without radiotherapy the little boy could die within a few months.