FISH is the biggest sticking point in Brexit talks now as Boris Johnson wants control over its waters back while the EU wants access to the fishing waters.
However, Britain and the EU have made good progress in talks on a last-minute trade deal.
The UK left the EU in January but the two sides are trying to clinch a deal that would govern nearly a trillion dollars in annual trade before informal membership - known as the transition period - ends on Dec. 31.
"We're in intense negotiations with the EU - we've made real progress," Trade Secretary Liz Truss said. "We're making good progress on the negotiations."
"But if the EU aren't prepared to do a deal that allows the UK to retain its sovereignty, then we will go to Australia style terms, and I think that's perfectly reasonable."
The chief negotiators of Britain and the European Union, Michel Barnier and David Frost, meet on Friday for intensive negotiations.
After some progress on competition guarantees including state aid rules, the hardest issue remains fish:
Ireland's foreign minister said he believed Britain and the EU could reach a trade deal now the talks were back on track, but added the issues of fair competition and fisheries hampering an accord were "still very much there".
Asked if there would be a deal, Britain's junior finance minister Stephen Barclay said he hoped there would be but fishing was a key sticking point.
"(The) deal needs to reflect that fact that we're leaving the EU, we will regain control of our fisheries," he told Sky.
At a briefing with diplomats in Brussels on Wednesday(21), Barnier said he was only worried about fish, one person who participated in the closed-door meeting said.
"Fish is now the thing to tackle. The other elements seem doable, more or less," the diplomat said.
While fishing alone contributed just 0.03 per cent of British economic output in 2019, it is an emotive subject as many Brexit supporters see it as a symbol of the regained sovereignty that leaving the EU should bring. Combined with fish and shellfish processing, then the sector makes up 0.1 per cent of UK GDP.
For French fishermen, British waters are crucial and being locked out would cause trouble for French president Emmanuel Macron.
Meanwhile, Britain and Japan formally signed a trade agreement on Friday(23), marking the UK's first big post-Brexit deal on trade, as it continues to struggle to agree on a deal with its closest trading partners in the EU.
