The chief executive of the transgender children’s charity Mermaids has resigned, the organisation has said.

Susie Green’s departure after six years was announced in a statement on the charity’s website, but no explanation was given about what was behind the move.

Chair of trustees Belinda Bell said: “The trustees are very grateful to Susie for everything she has done over the last six years to support trans, non-binary and gender-diverse young people and their families, and to build Mermaids into the organisation it is today.

“We wish her all the best for the future.”

The charity said an interim chief executive would be appointed shortly.

Mermaids was founded in 1995 and staffed by volunteers until 2016.

Ms Green became its first member of staff. The Leeds-based charity, which also has an office in London, has about 44 staff members and 110 volunteers.

Mermaids has launched an appeal against the Charity Commission’s awarding of charitable status to LGB Alliance, which has been critical of “gender ideology”.

It is understood to be the first time one charity has attempted to strip legal status from another.

Ms Green’s departure comes after the charity had recently been the subject of media scrutiny.

A question was also raised about Mermaids in Parliament during Prime Minister’s Questions in October.

Then-prime minister Liz Truss said that allegations about Mermaids “should be properly looked at” after a Conservative MP called for a police investigation into the organisation.

Miriam Cates, the MP for Penistone and Stocksbridge, told MPs that “serious safeguarding failures” by Mermaids had come to light, such as reportedly sending chest-flattening devices to young girls against their parents’ wishes.

The Telegraph had reported the charity – which supports transgender, non-binary and gender diverse children and their families – had been offering binders to children as young as 13 despite their parents saying they oppose the practice.

Chest-binding is opposed by some groups over fears it causes breathing difficulties, back pain and broken ribs.

The newspaper also reported the Mermaids online help centre had been offering advice to teenagers that hormone-blocking drugs are safe and “totally reversible”.

The Charity Commission opened a regulatory compliance case into the organisation after a number of complaints – it is the first step taken by the regulator, and not a finding of wrongdoing.

The Times has also reported that Dr Jacob Breslow, a trustee, gave a presentation in 2011 on “a science-informed understanding” of people attracted to children.

In a statement last month, Mermaids said his appointment was a mistake and Dr Breslow had resigned.

Ms Bell said that steps were being taken to “ensure we are more rigorous in future”, adding: “We want to apologise for the distress and concern this news has caused. 

“It is clear that Dr Breslow should never have been appointed to the board, and as chair of the trustee board I am horrified that he was.”