Britain could be rushed into signing worthless trade agreements with the European Union post-Brexit, because ministers are struggling to understand the complexity of the task facing them.

Steve Woolcock, of the London School of Economics, who is preparing civil servants from Liam Fox's international trade department, was quoted as saying by The Times that political pressure could undermine the quest to reach any meaningful deal.

According to Woolcock, the government's desire to reach a trade agreement with the EU within the two-year negotiation period, before moving on to agree individual deals with other states could be harmful.

"The greatest danger in trade policy at the moment is that there's a political imperative to conclude agreements with other countries to show that Brexit works," he said.

"These are unlikely to have many economic benefits or enable the UK to keep up with other preferential trade agreements."

Futhermore, Woolcock warned, while most of the attention has so far been placed on free trade agreements, common standards and regulations were likely to be a much sterner challenge for the UK's Brexit negotiators. "At a political level there is still no recognition of the difficulties," he said. "All the debate was about tariffs. But tariffs are a minor aspect of doing business internationally today."

The LSE professor added that trade agreements were more dependent on reducing non-tariff barriers stemming out of different rules and standards, than on removing tariffs on imports and exports. "The problem is on regulatory issues," he said.

"The UK has to negotiate some kind of arrangement that can help to continue to ensure that UK regulatory standards will still be seen as equivalent. Without that it's too easy for the EU to simply say 'no, that doesn't apply anymore'."

Woolcock's words came as Michael Barnier, the EU's chief Brexit negotiator warned Britain that "no deal" on its talks to leave the European Union would mean long immigration queues at UK airports and ports.

The veteran French politician said not agreeing a deal would also lead to the disruption of a number of supply chains into the UK, "including the suspension of the delivery of nuclear material to the UK".

"It goes without saying that a no-deal scenario, while a distinct possibility, would have severe consequences for our people and our economies," Barnier wrote in a column in the Financial Times. "It would undoubtedly leave the UK worse off."