The UK will have less access to the EU single market than Pakistan, Rwanda or Yemen if Brexit negotiations fail, a leaked Treasury document reveals.
The prediction comes as MPs are due to vote on whether to overturn a House of Lords amendment on Monday (13 March) that would give the House of Commons a "meaningful vote" on the final outcome of EU negotiations.
Prime Minister Theresa May has resisted the amendment and repeatedly said that "no deal would be better than a bad deal", but such an outcome would mean economic disaster and years of uncertainty, according to the report.
The document was leaked to the Independent after the department carried out an analysis of Brexit's impact into what would happen if no deal was struck with Brussels within the two-year period.
Such an outcome would mean Britain's access to the market would be "terminated" and "would take years" to strike new arrangements that match the current terms, causing a "major economic shock" to the UK economy.
The document said: "UK agricultural exports to the EU would face new tariffs of 14.4% on average, and non-agricultural goods an average tariff of 4.3% – enough to undermine the competitiveness of some UK businesses.
"The UK would have less access to the [EU] single market than Pakistan, Rwanda or Yemen. The EU would trade with the UK on the same terms as it does with countries like China – with no preferential access."
Additionally, the document said that consumers would no longer benefit from the end to mobile phone roaming charges, EU compensation for delayed flights or cancelled holidays, or protections covering purchases in an EU country.
Instead, the UK would have to rely on the World Trade Organization (WTO) for its competitive arrangements and trade agreements.
"After we left the EU, we'd need to renegotiate the terms of our WTO membership," the document added. "This would trigger bureaucratic negotiations with other WTO members, lasting for months or years… This could be a very complex exercise involving a review of every tariff line – over 5,000 – to determine what rate the UK wished to apply."
In a separate report published on Sunday (12 March), the cross-party Commons Foreign Affairs Committee slammed May for failing to prepare a Brexit backup plan as she gets set to trigger Article 50 this week.