Consumers need reassurance that Brexit will offer them a better deal on issues such as food safety, energy bills, travel rights and roaming charges, a watchdog has said.
Which? said the UK should seize the opportunity to become "truly world-leading" in protecting consumers as it negotiates Brexit.
Negotiators needed to pay "immediate attention" to maintaining the UK's "world-leading" consumer rights framework, food quality and safety standards and the security of supply of affordable energy, the group said as it launched its Consumer Charter for Brexit.
They also needed to deliver on maintaining access to the EU common aviation area to protect flight choice and keep travel costs down, ensuring holidaymakers have access to reciprocal healthcare and protecting mobile roaming in Europe.
It said the UK needed an economy where consumers were supported by high levels of rights and protection, with "greater access than ever before to quality, affordable products and services".
Which? chief executive Peter Vicary-Smith said: "We want to work with ministers and businesses to deliver on the priorities that matter most to people in their daily lives and reassure consumers that their existing rights will be protected and standards won't be compromised.
"With control over all aspects of consumer protection the UK should seize this opportunity to be truly world-leading.
"Today we set out a plan that we believe can deliver a Brexit that puts consumers first. And that is what the success of Brexit will ultimately be defined by - what it delivers for consumers."
Huw Evans, director general of the Association of British Insurers, said: "It's critical people planning trips abroad after Brexit are given urgent clarity about what happens in the event of 'no deal'.
"Agreeing a transition deal later this month would help provide that but if it doesn't happen then the onus must be on holiday companies and airlines to be transparent about any risks, and to explain up-front how they would intend to compensate customers.
"Travel insurance will continue to be a vital purchase for those going overseas but its function is not to bail out holiday firms who aren't being straight with their customers."