Calls have been made to lift freight restrictions at UK ports “within the next 24 hours”.
On Sunday night, France closed its border with the UK for 48 hours, after concerns were raised over the discovery of a new strain of Covid-19.
This has meant no accompanied lorries are able to enter Europe via France.
James Withers, chief executive of Scotland Food & Drink, has said urgent action is needed to protect “perishable products worth millions”.
He said: “We need the ban on freight moving across the English Channel lifted in the next 24 hours so products can start moving by Tuesday morning at the latest.
“We have heard from companies with dozens of lorries now stuck, having travelled overnight to Dover or the Eurotunnel which are now shut to incoming traffic.
“They are carrying perishable products worth millions and the clock is ticking for that product to survive these delays.
“We estimate there will be over £5 million of Scottish food that would be been heading into France daily this week.”
He continued: “The timing of this could scarcely be worse for many businesses.
“There are critically important markets scheduled for Wednesday in France and Spain as part of the big pre-Christmas sales rush.
“As things stand, Scottish seafood exports will not reach them, which will compound the losses businesses have already suffered as a result of Covid this year.”
He added: “Businesses importing ingredients and fresh products will be hugely concerned if this lasts longer than 48 hours and incoming freight is disrupted because drivers won’t risk getting stuck in the UK.”
Scottish Government export figures released last week indicate France remains the single largest importer of Scottish food and drink products.
Exports to France for the first nine months of 2020 are already down 11.3% on the same period the previous year.
Mr Withers added: “I entirely understand the concerns of France and others about this new strain of Covid-19. We’re all worried about it.
“However, France stands alone in introducing a freight ban, other EU countries have just focussed on restriction the travel of the general public.
“We need the UK Government to urgently agree a protocol for freight movements, with perhaps the testing of drivers able to provide the necessary reassurance.”
The Scottish Seafood Association echoed his call, with chief executive Jimmy Buchan saying the move was a “disaster” for companies already hard hit by the first wave of the pandemic.
Mr Buchan said: “Not just for the sake of SSA members, but for the millions who enjoy our world-class seafood across Europe, we call upon the French, at the very least, to allow perishable goods to flow.
“These few days in the run-up to Christmas is hugely busy for a lot of our members, with seafood destined for all parts of the Continent going via France.
“Traditionally in Spain seafood is a major part of Christmas Eve, and most of our exports get there via the Eurotunnel or Dover-Calais routes, so it is a disaster for our members.
“For example, one relatively small company has £230,000 worth of live shellfish stuck at the border, with a further £250,000 worth ready to go.
“Another bigger outfit has £500,000 worth at Dover, and an additional £750,000 ready for despatch, all of which are just-in-time exports for the Christmas market.”
Scottish company Lochfyne langoustines said it had “hundreds of thousands of pounds” of product heading to Dover.
In a tweet, it wrote: “There will be Vivier trucks from all over Scotland heading in that direction, millions of pounds worth of seafood at the time of the most important market of the year the last one before Xmas.
“Jesus if BREXIT wasn’t going to put us out of business by Tuesday this week we will be.”
In a post shared on Twitter by the French Embassy in the UK, French Transport Minister Jean-Baptiste Djebbari said: “In the next few hours, at European level, we’re going to establish a solid health protocol to ensure that movement from the UK can resume.
“Our priority: to protect our nationals and our fellow citizens.”