Proposed legal reforms on relationships risk inadvertently drawing cohabiting couples into marriage-style commitments without their knowledge, critics have warned.

Under plans put forward by the Government, a formal system would be introduced to regulate financial outcomes following the separation of unmarried partners.

In addition, the measures would grant surviving partners the legal right to inherit an unmarried partner's assets should they die intestate.

The changes would also ensure pre-nuptial agreements become legally binding.

However, fresh polling from Survation reveals that nearly three-quarters of people (72%) have minimal or no awareness of these planned updates.

The survey of 2,060 UK adults also demonstrated that public opinion remains divided over whether the proposed measures are a good idea.

Of the surveyed group, 43% believed unmarried cohabiting couples should have a set of rights which apply automatically unless they choose to opt out, while the same proportion, 43%, believed the new framework should only apply if couples actively agree to opt in.

On the proposal to give qualifying cohabiting partners inheritance rights when their partner dies intestate – without a valid will – 29% opposed the proposal and 33% backed it, with a further 29% saying they neither supported nor opposed it.

One participant in the research said lawyers “would love” the reforms because it would create a “vast new field of work” for them and another said: “I’m not married and don’t want to be – I’m my own person.”

Backers of the proposal said they thought “cohabiting couples should have some legal protections” and that reforms “would mean women are protected” when relationships break down.

A Ministry of Justice consultation on the proposals closes on Friday August 14.

Baroness Deech, a crossbench peer, said she was concerned by the “lack of consent and indeed knowledge” around the Government’s proposal.

She said: “People don’t know about it.

“Not only do they not know about it, they will not have consented.

“And it seems to me absolutely fundamental that if you are in a relationship which is going to put everything that you own, your entire life, in the hands of a new law, you should consent.

“Marriage requires consent.

“Civil partnership requires consent.

“Property dealings require consent, and so should any new legal status based on cohabitation, so it’ll be something – if it passes – brand new.

“And people may go in to it knowing nothing about it, come out knowing nothing about it, and then find to their detriment that there is a legal framework that the state has imposed on them without their consent.”

If the Government brings in its proposals, couples will have a new legal framework after three years of living together, without having to sign an agreement or say “I do”.

Cohabiting partners would also have access to the framework if they have a child together.

Opting out of the framework would require the consent of both couples.

Break-ups would not be the same as divorce, because the starting assumption that assets are to be split 50:50 would not apply.

Individual partners would keep assets they legally own and courts would only intervene to decide whose property is whose to meet an individual’s defined needs.

The Government has said its objectives are around “protecting the vulnerable”.

Its consultation document reads: “Women are disproportionately more likely to reduce their earnings or leave the workforce to take on caring responsibilities, leaving them financially exposed if a relationship ends.

“A needs-based approach ensures they are not left unable to secure housing or maintain a reasonable standard of living because of that choice.

“It also offers victim-survivors of domestic abuse, including economic abuse, a realistic pathway to safety by ensuring they can access support after leaving a relationship.”

But Lady Deech said that the proposal could instead lead to “a situation where one partner is holding the other one, as it were, to ransom” because opting out of the framework would require the consent of both partners.

The crossbencher also said “opting out would be very difficult” because both members of the couple would need to consent and seek potentially costly legal advice.

She earlier warned that an “extraordinary” number of people did not know about the proposals, the polling suggested, which could result in a Waspi-style campaign for redress in the future.

The Waspi (Women Against State Pension Inequality) campaigners have called for compensation, after changes to the state pension age which the Parliamentary and Health Service Ombudsman has previously found to have been poorly communicated.

A Ministry of Justice spokesperson said: “This new framework will offer eligible cohabiting couples, in committed romantic relationships, a distinct and different set of rights from married couples, helping to preserve the sanctity of marriage.

“With more than 3.5 million cohabiting couples and widespread confusion about their rights, it addresses a clear gap in the law.

“Unlike marriage, there would be no automatic 50:50 split of assets on separation, and people would generally keep what they legally own.

“This is an open consultation, inviting views from the public and experts, and the Government will consider the findings of the consultation carefully before finalising policy.”