Hauliers are facing "an administrative nightmare" over post-Brexit trade in Northern Ireland, a House of Lords committee has been told.
The European Union Committee was in Belfast today to hear the concerns of local representatives from the freight sector, ports, ferry operators and Belfast International Airport.
There was a unanimous demand for clarity from the Government over what is expected of firms once the Brexit transition period ends in December.
The UK's withdrawal agreement with the EU means checks and controls will be required for goods travelling from Great Britain to Northern Ireland.
A tariff would also be imposed if the items are at risk of travelling on to the Irish Republic.
Northern Ireland Secretary Brandon Lewis has insisted this will not amount to a border in the Irish Sea and that local businesses will have unfettered access to trade.
But this was questioned by Les Stracey, director of corporate affairs for Stena Line.
He told the House of Lords committee that 540,000 freight units pass through Belfast Harbour with Stena Line a year, of which 97% are UK to UK trade.
"We're uncertain when it comes to checks... will it be for the 3% or for the 100% of goods?," he asked.
With sailings usually taking 90 minutes, he said there was "great concern" about how the Stena Line timetable would be affected.
He called it "a nonsense" that ferry operators could be forced to collect data for hundreds of trailers, amounting to "an administrative nightmare".
Mr Stracey called for a digital solution to stop any delays and avoid extra infrastructure costs.
He said: "We're running out of time to put systems in place, to put infrastructure in place."
Graham Keddie, managing director of Belfast International Airport, was asked about introducing exit declaration forms for goods going from Northern Ireland to Great Britain.
"Do you want the brutal answer? It's just to get rid of it," he said.
"It's going to be very difficult because it is bureaucracy and it does limit our competitiveness."
He said any extra red tape and likely need for increased infrastructure would be "a double whammy" in which customers would pay more for a lesser service.
Pamela Dennison, chair of the Freight Transport Association Northern Ireland, issued a similar warning.
"I despair at what's going to come (in) January," she said.
She said an increased responsibility for paperwork would place considerable pressure on the business: "If that paperwork goes wrong, it's myself and my drivers that will be affected."
She said that local hauliers who deliver to both the UK and Ireland were in "a very volatile area" as they waited to juggle both the Northern Ireland protocol and EU regulations.
Any extra costs from the new arrangement, she said, "will end up on the consumer's door and will make it unfeasible to buy goods from Northern Ireland".
"We will have to very careful how we manage this moving forward," she added.
Asked for a message for the Government, she replied: "Stop telling businesses what you think they want to hear and tell them what's going on".
The committee later heard from David Phinnemore, professor of European politics at Queen's University Belfast.
He was asked what goods entering Northern Ireland would be considered at risk of being transported to the Irish Republic and therefore subject to a tariff.
"The starting point is very clear: everything is at risk," he said, until the EU can be persuaded otherwise.
"Businesses are crying out. The last three years have been about uncertainty.
"I don't think you'll find any economic operator who thinks that this is a good deal for Northern Ireland."
The UK was today warned not to renege on the commitments on the Irish protocol as the EU gathered to discuss its position on the imminent trade talks.
Irish foreign minister Simon Coveney said the EU made a "generous and fair" offer to the UK which must be honoured.
"Michel Barnier and the Irish government are at one on this. The withdrawal agreement involves significant commitments in the context of Northern Ireland through the Irish protocol that both the EU and the UK need to follow through on," Mr Coveney added.
His comments follow reports that Prime Minister Boris Johnson has ordered his Brexit team to find ways to "get around" the protocol.
Downing Street has insisted, however, it will honour the terms of the deal.