One of the founders of the world’s oldest breastfeeding support charity has quit in protest at its inclusion of transgender women.

Marian Tompson denounced La Leche League International as an ‘organisation that has become a travesty of my original intent’.

In a damning resignation letter from the board of directors, the 94-year-old condemned the group’s shift from focusing on mothering to ‘indulging the fantasies of adults’.

She wrote in a letter to senior figures at La Leche League (LLL): ‘From an organisation with the specific mission of supporting biological women who want to give their babies the best start in life by breastfeeding them, LLL’s focus has subtly shifted to include men who, for whatever reason, want to have the experience of breastfeeding, despite no careful long-term research on male lactation and how that may affect the baby.

‘This shift from following the norms of nature, which is the core of mothering through breastfeeding, to indulging the fantasies of adults, is destroying our organisation.’

She said she had tried to get the board to change its approach but admitted there is ‘nothing I can do’.

However, she added that she hoped to return to the organisation – which she helped found in 1956 to improve breastfeeding rates in the USA – when it returns to its ‘original mission and purpose’.

Last night Helen Joyce of British women’s rights charity Sex Matters said: ‘The situation at La Leche League is one of the starkest examples of how gender-identity ideology turns organisations upside-down.

‘By including men who want to breastfeed in its services, LLL is destroying its founding mission to support breastfeeding mothers.

‘It also goes against the wishes of many mothers, group leaders and trustees around the world, who have been fighting to convince LLL International to hold fast to its woman-focused mission, including here in the UK.’

Earlier this year, the Mail told how the British arm of La Leche League had been forced to call in the Charity Commission regulator in a dispute over its trans inclusive policy.

There were claims of ‘harassment and bullying’ over a policy to include trans women in meetings.

Directors raised concerns that the diktat from the global organisation could mean volunteers are also forced to give advice to trans women wishing to breastfeed.

One of its trustees of La Leche League GB has now quit over the row.

Miriam Main wrote: ‘I do not recognise LLL in the bullying, lies, and cruelty of recent times and this has been unreasonably hard to endure.’

A spokesman for the British charity said: ‘The LLLGB Council of Directors are aware that Marian Tompson has resigned from the La Leche League International Board.

‘We would like to take this opportunity to acknowledge the role Marian Tompson has taken both in founding LLL and her tireless global work in the wider field of breastfeeding support for almost seventy years.’