A decision to house trans inmates in women's prisons will be reviewed after a new report criticised the policy.

The Scottish Prison Service said it would hold a consultation after research was published by a leading former civil servant.

There are 15 trans women inside Scotland's jails - around half of which are housed in female prisons. None of themn have undergone sex reassignment surgery and none have legally changed their gender.

One prison worker told STV News that prisoners were regularly being subjected to displays of "sexualised behaviour".

In her report, Edinburgh University researcher Lucy Hunter Blackburn said there was a lack of consideration given to the needs of women prisoners.

She said: "I'm absolutely astonished that a policy intended to move prisoners from the male estate into the female estate took no account of possible harms and risks to women.

"We already know that female prisoners are very vulnerable and have very high instances of mental health problems and histories of sexual and physical assault."

The prison worker, who asked to remain anonymous because she isn't authorized to speak to the media, said some inmates had threatened to rape prisoners and staff.

James Morton, of the Scottish Trans Alliance, worked alongside the Scottish Prison Service (SPS) to develop the policy of housing trans women in female jails. He said there was "loads of discussion" to make sure female prisoners weren't "inadvertently negatively affected".

Mr Morton added: "It doesn't have any kind of blanket requirement that a person who says they're trans is automatically transferred to a different estate.

"It's all encouraging risk assessment and individualised decisions and making sure that everything is done appropriately."

The SPS said it was committed to reviewing the policy and holding an open consultation.

Tom Fox, head of corporate affairs for the SPS, said: "We've adopted an individualised approach to the risk assessment process. We look at the totality of circumstances.

"We look at the safety and well being of the individual and the environments that they are going to be living in.

"Our prime consideration has got to be that everyone living in our care is safe and feels safe in that environment.

"We've operated this policy successfully for a number of years and we've done it with compassion and understanding of the complexities of these issues."