British and European officials will discuss the future options for the UK's relationship with the EU, Business Secretary Jonathan Reynolds has told the BBC.
Officials on both sides are expected to begin discussions about a range of options, including free movement, before the EU summit on 20 November.
However, Downing Street has insisted the government's current focus is on achieving new deals in areas such as food and youth mobility at the summit.
Reynolds said no "assumptions" had been made about what the UK's future relationship with Brussels could look like.
Andy Burnham has said he wants an "honest discussion" about the prospect of returning to free movement between the UK and EU and on Monday left the door open to a potential referendum on the issue.
However, he has been clear any major changes to the UK-EU relationship would require a mandate at a general election, which is due by 2029.
The prime minister has vowed to stick by the red lines in Labour's 2024 manifesto, with no return to freedom of movement, the EU single market or customs union, for the duration of this parliamentary session, which will end by 2029.
Freedom of movement, which allows EU citizens to travel, live, study and work in any member country, is a precondition of membership of the EU's single market.
The single market enables goods, services and people to move freely between member states, with countries also applying many common rules and standards.
Speaking to BBC Radio 4's Today programme, Reynolds said current discussions ahead of the summit are around food and drink, electricity and emissions trading.
He said: "What the prime minister has also said, quite rightly, is we face a series of policy changes on the European side that will affect us.
"We need to get as little uncertainty as possible, we need to have a way to resolve what our long-term relationship will be and he is going to set that out after the summit.
"He is going to be frank with the British people about what the trade-offs are but no assumptions have been made on that."
Pressed on whether UK officials are talking to the EU about freedom of movement Reynolds said: "They will be talking to them about what the future options for our relationship might be.
"But here and now, the focus should be on the summit and the tangible difference improvements we're going to make."
However, Labour MP Melanie Onn, whose constituency Great Grimsby and Cleethorpes backed leaving the EU, told the same programme Burnham risked losing trust by talking about going beyond the 2024 manifesto at a future election.
"I don't think that the scars have healed for many people around the country so I do think this is an unnecessary conversation to be having at this time," she said.
Onn, who lost her seat in 2019 to the Conservatives but won it back in 2024, warned against re-opening the conversation, saying: "Trust is incredibly important, it's hard-earned and easily lost, and on this matter I think that we should tread incredibly carefully."
Reform UK leader Nigel Farage told BBC Breakfast that "Andy Burnham has no mandate to be in Brussels, to be negotiating any of this" and called for the prime minister to put his ideas to the public in a general election.