The UK's human rights watchdog has sent a delegation to the UN in Geneva to raise concerns about the country's record on torture.
The Equality and Human Rights Commission has criticised the UK and Welsh government's records on preventing inhuman and degrading treatment.
They have highlighted concerns about immigration detention, healthcare and youth custody as part of their submission to the United Nations Committee Against Torture.
The UK is the only European country with no time limit on immigration detention and concerns about its treatment of migrants have been put in the spotlight in the wake of the "hostile environment".
The watchdog has also called for the age of criminal responsibility in England and Wales to be raised.
The EHRC is one of a number groups who have submitted evidence to the UN for the country review which takes place every five years.
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In the UK children suspected of offences can be arrested and charged from the age of 10 under the existing rules.
This is lower than in many European countries and "inconsistent with accepted international standards", according to the Equality and Human Rights Commission (EHRC).
It says criminalising children at the age of 10 or 11 can have a detrimental impact on their wellbeing and development, and risks making them more likely to reoffend as adults.
The EHRC is calling for the age of criminal responsibility to be "significantly" raised.
David Isaac, Chair of the Equality and Human Rights Commission, said: “Everyone has the right to be free from torture and inhuman or degrading treatment. That is an absolute right. Failing to adequately protect people from such dangerous and harmful acts is not only a moral failure but breaches our existing international legal obligations.
“Increasing the age of criminal responsibility is crucial to stop very young children being exposed to the harmful effects of detention and to protect their future.
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“We must also introduce a 28 day limit for immigration detention to end unnecessarily long periods of detention which carry a huge cost for society as a whole and expose people who have already experienced significant hardship to further suffering.
“Improving Britain’s record on preventing ill-treatment in our own country is essential if we want to maintain our long-held reputation as a champion of equality and human rights globally.”
The EHRC have also highlighted concerns that the UK ensures there is no weakening of human rights as a result of Brexit .
