LONDON (Reuters) - Trade minister Liam Fox has dismissed Britain’s chances of using international trade rules to ensure tariff-free post-Brexit trade, rubbishing one of the options mooted by the front-runner to be the country’s next leader, Boris Johnson.

FILE PHOTO: Britain's Secretary of State for International Trade Liam Fox is seen outside Downing Street, as uncertainty over Brexit continues, in London, Britain May 21, 2019. REUTERS/Hannah Mckay/File Photo

Britain is due to appoint a new prime minister next month after Theresa May resigned having failed to deliver Brexit. The race to succeed her is currently led by Johnson, one of the most prominent figures of the 2016 campaign to leave the EU.

Johnson is running on a promise to deliver a new Brexit deal by Oct. 31, or if he cannot, to leave on that date without a deal.

Johnson said that if talks on a deal fail, he would push for a “standstill period,” during which trade with the EU would remain tariff-free, under a clause in the set of international rules called the General Agreement on Tariffs and Trade (GATT).

The plan was attacked by Fox, who is backing Johnson’s rival Jeremy Hunt, in an extract of a letter he published online on Tuesday.

Fox said the relevant section of the GATT, Article XXIV, would require the consent of the EU, with an agreed plan and schedule for implementation.

“A ‘no-deal’ scenario, by definition, suggests that there would be no mutual agreement between the UK and the EU on any temporary or permanent arrangement. In those circumstances Article XXIV cannot be used,” he said.

His criticism, which did not name Johnson directly, adds to scepticism also voiced last week by Bank of England governor Mark Carney and others.

Fox also said any such standstill agreement would not address “more complex behind-the-border regulatory issues affecting trade.”

Johnson himself acknowledged earlier on Tuesday that the EU’s cooperation would be required, but said it would be “bizarre” of the bloc to try to impose tariffs on British goods.