"We've been crystal clear that issues around our withdrawal and our future partnership are inextricably linked, and the negotiations so far have reinforced that view", the Department for Exiting the European Union said in the statement released Sunday.
It has confirmed it will publish a number of papers, including one on Northern Ireland's border and future customs arrangements. The EU's chief negotiator, Michel Barnier, warned EU ambassadors last month that the lack of progress meant talks on the future relationship with the United Kingdom, including a free-trade agreement, may not be possible by the next leader's summit in October, and may have to extended. The two sides will be looking for a solution to those issues at the next round of talks due at the end of this month.
The government says it hopes to persuade the 27 other European Union nations to start negotiating a "deep and special" future relationship that would include a free trade deal between Britain and the EU.
A British paper focused on "issues unique to Northern Ireland and Ireland" is expected ahead of the talks, but no further details of the proposal were provided on Sunday.
Free movement for Irish citizens in and out of Britain is expected to continue after Brexit, with the establishment of a Schengen-style area between Ireland and Britain created to resolve the border problem. The Brexit department declined to comment on the story.
Chapman said Friday "there is an enormous gap in the center now of British politics" that could be filled by an anti-Brexit force.
"But we are also clear that during this period our borders must continue to operate smoothly; goods bought on the internet must still cross borders; businesses must still be able to supply their customers across the European Union and our innovative, world-leading companies must be able to hire the talent they need, including from within the European Union".
The next round of talks is due at the end of the month, with both sides looking for progress towards a solution to three of Brexit's thorniest problems: how much Britain should pay to leave, what rights British and European Union citizens will have, and how to manage a land border to the bloc in Ireland. The first will be a proposal for new customs arrangements.
They write that there will be a "time-limited" transition period that would "further our national interest and give business greater certainty", but insist that Brexit will not be halted.
Prime Minister Theresa May formally triggered the Brexit process on March 29 and divorce negotiations officially began on June 19.
Some still dispute her approach, with former foreign minister for the now-opposition Labour party David Miliband and pro-EU Conservative MP Anna Soubry warning in Sunday newspapers of the economic "self-harm" of leaving the single market.