The UK can “replicate” its existing international trade arrangements outside the EU, cabinet minister Liam Fox has said.
The international trade secretary told the BBC the UK had had a “very positive response” from the World Trade Organisation.
He is to meet the WTO’s director general and make a speech in Geneva.
Mr Fox denied that he was planning for a situation in which the UK leaves the EU without a deal.
It follows reports of cabinet divisions over Brexit, with Chancellor Philip Hammond saying last month that no deal with the EU “would be a very, very bad outcome”.
Mr Fox told BBC Radio 4’s Today programme that he would warn against “the rising voices of protectionism around the world [and] make the moral case for trade” in a speech in Geneva.
He is expected to urge further liberalisation of the services economy, and will state that free trade agreements were not the only way to remove business barriers.
Mr Fox added: “As Britain leaves the European Union, as we take up an independent seat on the World Trade Organisation, we want our voice to be heard.”
He said he believed that talks with the WTO indicated that “we will simply replicate our current obligations under the European Union as we move into the United Kingdom as an independent member”.
If the UK leaves the EU without a trade agreement it could default to WTO rules, potentially facing tariffs on goods and services traded with the EU.
Mr Fox said the UK could “of course survive with no deal” but he wanted a “full and comprehensive deal” with the EU.
“The only reason that we wouldn’t come to a free and open agreement is because politics gets in the way of economics,” he argued.
Some MPs have called for the UK to remain in the EU’s single market and customs union after Brexit. Some non-EU European countries, such as Norway, are members of the single market.
Mr Fox said that he did not “have a problem” with a transitional Brexit deal, which he described as an “implementation phase” but insisted: “You can not leave the European Union and be in the single market and the customs union.”
BBC political editor Laura Kuenssberg said Mr Fox’s apparent acceptance of “some kind of transition” indicated “a change in tone from Brexiteers” since the general election.
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Other ministers “believe they have comprehensively won the argument about the requirement to have a transition deal”, she added.