Everything will not go to "hell in a handcart" if there is no UK-EU trade deal at the end of the year, an economist has told Welsh MPs.
Cardiff University's Patrick Minford said that there were "all sorts of possible transitional arrangements".
However, another academic warned there could be food shortages similar to those early in the Covid-19 pandemic.
The UK has full access to the EU single market until 31 December, to allow time for a trade deal to be agreed.
The United Kingdom is currently in a transition period, after leaving the bloc on 31 January, and is still bound by EU rules.
Prof Minford, a strong supporter of the decision to leave the European Union, was responding to predictions of food shortages and long delays at ports, including Holyhead and Fishguard, if no new trade agreement was reached.
Giving evidence to the Welsh Affairs Committee, Prof Minford said: "It's not a binary thing, there wouldn't be complete lawlessness and everything going to hell in a handcart."
He said it was not the case that the European Union "will be so neglectful of their own economic interests that they, in the case of no deal, will simply go ahead and blockade things and stop stop stop getting through, which would be economically hugely against their interests".
Prof Minford said he did not think there would be food shortages because the EU would follow World Trade Organisation (WTO)) rules and there would also be "economic interests" preventing supplies running out.
"Spain, which exports an awful lot of agricultural products to us, they're not going to want them to rot on the docks and not get through to consumers," he said.
"They are part of the EU, and there are a lot of EU exporters who have a strong interest in law and order, and the imposition of WTO rules, so that the ports aren't clogged up illegally against the seamlessness requirements of WTO rules."
'Stuck in a truck somewhere'
However Dr Ludivine Petetin, a Cardiff University senior law lecturer, said that if there was a "really abrupt change" in trading circumstances, as a result of no deal being agreed, there could be food shortages.
This was because the world was "working under" a "just-in-time supply chain", she told the committee.
"This would mean that we could have some food shortages, a bit like we did during Covid-19 right at the beginning," she said.
Dr Petetin said this was "simply because you would have, all of a sudden, all this paperwork, all these inspections that would be coming in".
"And the problem is that when we are talking about agricultural food products, these are often perishable.
"If you think about all the fruit and veg we import from Spain and the Netherlands, I'm just going to the extreme here, stuck in a truck somewhere."
While the committee was meeting, Welsh Government Minister for European Transition Jeremy Miles issued a statement saying the risk of the UK trading with the EU "under nothing more" than WTO rules "remains uncomfortably high".