Construction of a UK-funded wall near Calais' so-called Jungle migrant camp will begin soon, the Home Office says.
Dubbed the "Great Wall of Calais" by some media, the 4m (13ft) wall will run for 1km (0.6 miles) along both sides of the main road to Calais port.
Road hauliers called the wall a "poor use" of public money.
Home Secretary Amber Rudd told MPs that while the UK provided money to help secure Calais, it was up to the French to decide which measures to use.
Work is expected to start this month, with the wall due to be finished by the end of the year.
Numerous fences have been built to protect the port, the Eurotunnel terminal and train tracks on the other side of Calais, and the BBC understands the wall will not replace any of those.
Ms Rudd told the Home Affairs Committee the wall was "not a new initiative", but what mattered was making sure the French had the right amount of security to prevent "illegals" trying to get to the UK.
"We support the French with money to help them do that," she said. "It is up to them how they decide to secure their borders in Calais and around it."
Labour committee member Chuka Umunna suggested the French were inspired by US presidential hopeful Donald Trump - who wants to build an "impenetrable, physical, tall, powerful, beautiful, southern border wall" between the US and Mexico.
Ms Rudd replied: "I couldn't possibly comment on that."
Home Office minister Robert Goodwill told the committee on Tuesday that security at the port was "being stepped up with better equipment".
"We are going to start building this big new wall very soon. We've done the fence; now we are doing a wall."
But Richard Burnett, chief executive of the Road Haulage Association, called the plan a "poor use of taxpayers' money".
He said funding for a wall "would be much better spent on increasing security along the approach roads".
Vikki Woodfine, of law firm DWF, works with many hauliers and said a wall "isn't the answer".
"It is simply a knee-jerk reaction that is unlikely to make a difference in the long run - particularly since the route to the Calais port is already surrounded by fences and barbed wire," she said.
She said "chaos reigns in the Calais region", but the "real problem" was a lack of policing.
Many of the migrants living at the Jungle and other camps in northern France attempt to reach the UK by boarding lorries as they approach ports or the Channel Tunnel.
Last month, BBC footage showed people-smugglers wielding sticks and dragging a felled tree onto the main Calais port road to stop lorries and allow migrants to climb on board.
On Monday, French lorry drivers and farmers blockaded the main motorway route into Calais in a protest calling for the closure of the Jungle.