"He is not helping us and he is certainly not helping Charlie", he said. "All he has done is tarnish the reputation of two parents who have been trying to save their son and we are getting a stream of abusive messages because of it."

He claimed that a GOSH allegation that other parents were "harassed" related to a time when Mr Seton-Marsden had asked other "distressed parents" to sign a petition and the family were unaware it was happening at the time.

Mr Gard added: "We have always acted in Charlie's best interests and we have never slated GOSH publicly, in fact we have been grateful to the staff for their care despite some conflicting issues.

"All the quotes you read in the media criticising GOSH, have come from him, not us."

A source close to Mr Seton-Marsden maintained that he had always been acting with knowledge of the parents and said that he had never attempted to get anyone to sign a petition in GOSH.

A rally in support of Charlie was yesterday held outside the Royal Courts of Justice by the American pro-life lobbyists who have flown to Britain to back the family.

Gregory Mertz, from organisation CitizenGO who organised the gathering, said they were hopeful that Charlie would be given residency in the US when the House of Representatives voted on the issue at the beginning of next week.