Rules banning some transgender women from female prisons in England and Wales come into force on Monday, the justice secretary has said.
First announced by Dominic Raab in October, the ban will apply to trans women with male genitalia, as well as those who are sexual offenders.
Mr Raab has now said it will be extended to include trans women convicted of violent offences.
He said the measures would "improve safety" for prisoners.
Under existing policy already in England and Wales, transgender women prisoners are only placed in a women's estate after a risk assessment by a complex case board.
The new rules will apply whether or not offenders have a Gender Recognition Certificate.
Exemptions will only be made in the "most exceptional" cases and with the approval of ministers, the government said. They will be considered for inmates currently in the women's estate who are assessed as low-risk.
Transgender women who cannot be safely accommodated in a men's prison can be imprisoned in a specialist unit, the government added.
The LGBTQ+ charity Stonewall said it was vital that the prison service individually assessed all prisoners and carried out detailed risk assessments.
A spokesperson said: "Trans prisoners are a vulnerable population, and there is no evidence to suggest that the automatic placing of trans women in line with their sex assigned at birth is safer than an individualised risk assessment."
The reason the policy is coming into force on Monday, despite having been announced four months ago, is because it has taken "time to do it very carefully and assiduously", Mr Raab told Sky News on Sunday.
It comes after the case of Isla Bryson in Scotland - a trans woman who was found guilty of two counts of rape before she had changed gender.
Bryson, 31, was convicted in January and was taken to Cornton Vale, a female facility, where she was held in segregation while awaiting sentencing.
Following outcry from politicians and the public, she was moved to a male prison within days. But Mr Raab said the rules were not a reaction to Bryson's case.
He said the government wanted to have a "liberal, sensitive, tolerant approach" to the LGBT community, who he said "suffer a lot in this country" with mental health issues.
"We will introduce new rules which mean that any trans offender with their male genitalia intact, or who have been convicted of a sexual offence and, adding to that, if they have been convicted of a violent offence, they will not be allowed into the female prison estate," he said.
In the year ending March 2022, there were 230 transgender prisoners out of almost 80,000 prisoners in England and Wales, according to Ministry of Justice figures.
Of these, 187 reported their legal gender as male and 43 as female.
There were six transgender women in female estates.
Mr Raab has now said it will be extended to include trans women convicted of violent offences.
He said the measures would "improve safety" for prisoners.
Under existing policy already in England and Wales, transgender women prisoners are only placed in a women's estate after a risk assessment by a complex case board.
The new rules will apply whether or not offenders have a Gender Recognition Certificate.
Exemptions will only be made in the "most exceptional" cases and with the approval of ministers, the government said. They will be considered for inmates currently in the women's estate who are assessed as low-risk.
Transgender women who cannot be safely accommodated in a men's prison can be imprisoned in a specialist unit, the government added.
The LGBTQ+ charity Stonewall said it was vital that the prison service individually assessed all prisoners and carried out detailed risk assessments.
A spokesperson said: "Trans prisoners are a vulnerable population, and there is no evidence to suggest that the automatic placing of trans women in line with their sex assigned at birth is safer than an individualised risk assessment."
The reason the policy is coming into force on Monday, despite having been announced four months ago, is because it has taken "time to do it very carefully and assiduously", Mr Raab told Sky News on Sunday.
It comes after the case of Isla Bryson in Scotland - a trans woman who was found guilty of two counts of rape before she had changed gender.
Bryson, 31, was convicted in January and was taken to Cornton Vale, a female facility, where she was held in segregation while awaiting sentencing.
Following outcry from politicians and the public, she was moved to a male prison within days. But Mr Raab said the rules were not a reaction to Bryson's case.
He said the government wanted to have a "liberal, sensitive, tolerant approach" to the LGBT community, who he said "suffer a lot in this country" with mental health issues.
"We will introduce new rules which mean that any trans offender with their male genitalia intact, or who have been convicted of a sexual offence and, adding to that, if they have been convicted of a violent offence, they will not be allowed into the female prison estate," he said.
In the year ending March 2022, there were 230 transgender prisoners out of almost 80,000 prisoners in England and Wales, according to Ministry of Justice figures.
Of these, 187 reported their legal gender as male and 43 as female.
There were six transgender women in female estates.