Consenting adults should be able to undergo so-called conversion therapy, the government has recommended.

Setting out proposals for how they plan to crack down on “coercive and abhorrent” practices that seek to change sexual orientation or gender identity, the Government Equalities Office said: “We recognise there is a plurality of experience in this area and that there are adults who seek counselling to help them live a life that they feel is more in line with their personal beliefs.”

“We do not intend to ban adults from seeking such counselling freely, but consent requirements will be robust and stringent.”

Under the proposals, conversion therapy of all kinds will be banned in England and Wales for anyone under the age of 18, and adults who are vulnerable and not able to properly consent. The government said any type of the practice that involves physical or sexual violence is already illegal under existing legislation.

Further moves to clamp down on conversion therapy also promised include making it a potential aggravating factor that could lead to a longer jail sentence if prosecution is pursued, and creating new protection orders to take away people’s passport if there is substantial evidence they will be taken abroad to be subjected to the practice.

A consultation will run for six weeks, after which the equalities minister, Liz Truss, will decide on whether the plans should be amended. A bill will be drawn up by next spring, with the aim of putting it on to the statute book by May 2022.

Around 5% of people who responded to the national LGBT survey in 2017 reported having been offered conversion therapy, while a further 2% said they had undergone it.

Jayne Ozanne, who quit the government’s LGBT advisory panel in March and has direct experience of conversion therapy, said she welcomed the consultation’s launch, but added she was “deeply concerned about the loophole it creates by allowing adults to consent to these harmful and degrading practices”.

Ozanne told the Guardian: “The consultation document makes little mention of the harm that religious practices are known to cause, nor does it recognise that the government’s own research has shown that these form the majority of such practices in the UK – instead it focuses on ‘talking therapies’ in clinical settings.

“This is a grave mistake and will come as a severe blow to all survivors who have bravely shared their stories in the hope that the government will protect others.”

She added: “We have been saying this to government for years … but sadly few in government want to engage with these facts.”

Alicia Kearns, a Conservative MP who has long campaigned for a conversion therapy ban, said the government’s plans would “protect LGBTQ+ people from bigotry and quackery packaged up by sinister charlatans to snare and profit off the vulnerable”.

She praised the “robust proposals” but added: “I remain unconvinced that anyone can consent to such an abusive practice, and will look closely at the proposed ban to ensure that victims and survivors get the protections they need and deserve.”