Couples are paying up to £60,000 for babies born via surrogate mothers despite a ban on commercial surrogacy, a study has found.

The UK’s “altruistic” system means surrogates may be reimbursed only “reasonable expenses”, which experts say should cost families no more than £12,000.

However, the world’s largest fertility conference heard that British courts routinely sign off costs of far greater value if they can be persuaded the child is going to a good home.

The survey of 177 sets of parents by the University of Kent showed that the largest group - 30 per cent - paid between £20,000 to 30,000 during the surrogacy process, while 25 per cent paid between £10,000 and £15,000, and 21 per cent paid £15,000 to £20,000.

Meanwhile seven per cent paid up to £40,000, and in five cases couples paid up to £60,000.

The law does not set a limit for “reasonable expenses”, however cash transactions are supposed to be scrutinised by judges when they make parental orders, the process that transfers legal parenthood from the surrogate to the intended parents.