A senior Tory has called on Theresa May to clarify if Britain will try to remain a member of the single market and the customs union.
Treasury committee chairman Andrew Tyrie said the sooner the Government can provide clarity over key Brexit issues, the better.
Mrs May has played down suggestions that she was ruling out single market membership by insisting on the UK regaining control over immigration.
In a speech at the DLA Piper Future of the City dinner, Mr Tyrie said the PM's plan to set out broad objectives soon was welcome, "if not overdue".
"A document is needed that enables a full and considered consultation with Parliament and the public," he added.
He also called for the premier to set out whether the Government will seek a transitional deal as it negotiates Britain's exit.
He said: "First, there is the question of whether the UK will seek to remain a member of the single market, or if not, seek at least to obtain equivalent access for trade in goods and services.
"Clarity on this point would enable Britain to start making a crucial point to our counterparties: the four freedoms of the single market are neither immutable nor irretrievably interdependent. In any case, the EU will have to address the consequences of flows of people within its borders on a scale not envisaged when the Treaty of Rome was signed in 1957."
"Second, the UK needs to decide whether to participate in a customs union with the EU. If not binary, most of the options are relatively clear cut," he added. "From inside a customs union, the UK would continue to share the EU's common external tariff, leaving little scope for global leadership in free trade. From outside, the UK would have the freedom to pursue an independent trade policy, albeit at the cost of new administrative impediments to UK-EU trade.
"Third, and perhaps most important of all, the Government should take the opportunity to clarify whether the UK will seek transitional arrangements under Article 50. This provides that the EU Treaties may continue to apply to the UK, for an agreed period, after the withdrawal negotiations have been completed. This is a very important but apparently misunderstood provision."
He added: "In her New Year message, the Prime Minister rightly talked about securing a deal with the EU that commanded the support of both Leave and Remain voters. That matters a lot. There is almost certainly a majority in the country – and a cross-party majority in Parliament – for a continued close economic and political relationship with the EU from outside. Safeguarding the economic well-being of the country probably requires a relationship that is considerably deeper than that provided for under WTO rules.
"Given the need to build a broad-based support for its position, at home and abroad, the sooner the Government can provide clarity, the better."