Lawyers for a five-year-old boy born brain-damaged in a hospital in Germany, which was under contract to care for British soldiers and their families, are to take his case to the court of appeal tomorrow in an attempt to hold the Ministry of Defence responsible.

A high court judge ruled last April that the MoD could not be liable for the injuries to the boy, the son of a soldier now in Iraq, and his family must sue the hospital in the German courts.

Lawyers for the boy, who can be named only as "Child A" for legal reasons, will argue that the MoD, which contracted out hospital care for troops in Germany and their dependents after closing its military hospitals there, should pay compensation.

They say that under rules on referrals for treatment abroad to cut waiting lists, the NHS would be responsible if a civilian patient sent to the same hospital was injured through medical malpractice.

More than 30 other cases involving British service personnel or their families treated in Germany, Cyprus and Oman are on hold pending the outcome of A's case.

His lawyers say the MoD owed him a duty of care, which could not be delegated to others, to ensure a safe delivery. But the high court said the MoD's only duty was to exercise reasonable care in choosing the treatment providers.

A was born in June 1998 at the Gilead hospital in Bielefeld. German doctors have acknowledged that the delivery was negligent. His parents' marriage broke down under the strain of caring for him, and his mother, who has legal aid to bring the case, lives in England with A. His claim could be worth up to £3m in the British courts but damages are lower in the German courts.

David Poole, the family's solicitor, said: "It is the government's policy preference that patients travelling abroad for treatment should have the same remedies as patients receiving treatment in the UK.

A's mother said: "I am hoping that justice prevails."

The MoD said: "We always consider claims on the basis of legal liability. Where there is a legal liability we do pay compensation."