The Welsh and UK governments have clashed in a new row over how trade rules will operate post-Brexit.
UK government plans ask all four nations to accept rules and standards set by each other to ensure trade remains seamless across the UK.
The Welsh Government said it had not seen the plans and any system forced on Wales would be "deeply damaging".
UK Business Secretary Alok Sharma said the plans continued "hundreds of years" of a "seamless internal UK market".
The Welsh Government negotiated an agreement with the UK government in 2018 that means powers in areas such as food labelling, support for farmers and energy efficiency - currently regulated at EU level - will return to Cardiff.
The UK government has however said that devolved administrations will have to recognise the rules of all four nations, so as not to harm trade within the UK.
In a policy paper, it says this will ensure a level playing field for all firms regardless of which UK nation they are in, to ensure a UK-wide "internal market".
'A seamless UK internal market'
Mr Sharma told BBC Radio Wales Breakfast with Claire Summers: "What we are proposing today in the white paper is a continuation of what's happened over hundreds of years which is a seamless UK internal market."
He said the devolved administrations "have known the direction of travel" and the UK government would be "engaging with colleagues extensively across all the devolved administrations and getting their views."
He added: "The UK has some of the highest standards when it comes to the environment, animal welfare, food safety, and that is not going to change."
The Welsh Government said while it supported the principle of seamless trade any rules must be agreed by the devolved nations.
A spokesman said: "Any new system must have independent oversight and dispute resolution.
"Unfortunately, the UK government has not managed to share the paper with us, and Welsh ministers have had no recent discussions with the UK government on these issues.
"Any attempt to unilaterally impose a system will be deeply damaging."
But Welsh Secretary Simon Hart said Wales was a "vital part" of the UK's single marketplace and 75% of Welsh goods were consumed in the rest of the UK.
"Securing this internal market will ensure this trade remains seamless, safeguarding thousands of Welsh jobs," he said.
"It is vital for our shared prosperity and our ability to bounce back from the pandemic that people, products, ideas and investment continue to flow unhindered throughout the UK."
During a Commons statement on the legislation, Plaid Cymru MP Hywel Williams called it a "power-grab" transferring "vast powers over devolved areas to Tory ministers".
"Thirty-five years ago, in 1985, the then Tory European Commissioner's white paper detailed 300 legislative proposals to complete the European Single Market and that with a seven-year deadline," he said.
"On the 'UK Internal Market', this Tory government is giving a four-week consultation over the summer.
"Persuasive evidence, were it needed, that the UK internal market is first and foremost a convenient headline - a veneer lacking detail or a legal basis."
Welsh Government cancelled 'briefing'
After Welsh ministers had complained about a lack of consultation and not seeing the proposals before they were made public, it emerged that the Welsh Government had cancelled a meeting that would have given the first minister a briefing on the plans.
A spokesperson for the Welsh Government said: "Given the significance of the changes the UK government is planning to impose on Wales, we asked for a copy of the paper ahead of any meeting with the secretary of state for Wales.
"This would have allowed for a more meaningful discussion on these deeply damaging changes.
"Regrettably, this did not happen."
This is really all about who gets to decide things such as food standards after EU rules stop applying at the end of the year.
Ministers in Cardiff Bay are concerned about a hollowing out of devolution by the back door.
Take the proposal for a " mutual recognition principle" as an example -.. they say it effectively means the lowest common denominator wins because every UK home nation has to recognise every other home nation's standards.
So in the trade negotiations with the US - the proverbial chlorinated chicken issue - if the UK government negotiated a trade deal with the US allowing lower standard food into England, the Welsh Government couldn't stop it coming into Wales.
But the UK government insist they will protect British food and farming standards in the negotiations so the issue won't arise.