A 12-month grace period and urgent financial aid is needed to iron out problems with the post-Brexit Irish Sea trade border, hauliers said.
The Government must intervene with extra cash before jobs are lost at freight companies, the industry warned.
The end of the transition period has produced deep-seated structural problems which will not be quick to resolve, the Road Haulage Association (RHA) said.
Volumes of trade from the rest of the UK to Northern Ireland has fallen sharply and many suppliers are avoiding the route. Dozens of lorries have been left sitting in yards in Great Britain.
The UK Government insisted “goods are flowing effectively” between Britain and Northern Ireland.
But RHA chief executive Richard Burnett said: “This is a financial precipice haemorrhaging money.
“There needs to be financial intervention immediately.”
It is quicker to send goods between Northern Ireland and Spain than from the rest of the UK, the hauliers said.
New customs declarations were taking 12 hours, when hauliers were promised it would take 30 seconds.
Some drivers who can depart Irish Sea ports are having to produce 300 pages of paperwork, the transport firms added.
Dozens of staff helping with red tape are off sick because of coronavirus, the industry said.
Some freight companies are seeing a third of business disappearing, Mr Burnett added.
He warned: “There are going to be jobs lost, that is the bottom line here.”
He said issues encountered since the end of the transition period were not teething problems.
“These are significant structural issues.
“Government needs to intervene quickly with financial support to address this issue.”
Peter Summerton, managing director of haulage company McCulla Ireland, said these were not temporary problems.
He asked: “What are we trying to do? Break the Northern Ireland economy by breaking Northern Ireland hauliers?
“The trade imbalance cannot be maintained, it is not unfettered access.
“We can move product from Northern Ireland to Spain faster than we can move product from England to Northern Ireland.”
Another haulier, Paul Lutton, addressed a virtual meeting organised by the Labour Party on Wednesday.
He said: “I know we are insignificant to you in Great Britain, we are only a small town but we want to be part of Great Britain.
“You have said you can be, you are not helping us out.
“I am flabbergasted.”
The delays are caused by the post-Brexit Northern Ireland protocol, which means the country must follow the EU’s customs rules to prevent a hard Irish border.
A UK Government spokesman: “Goods are flowing effectively between Great Britain and Northern Ireland and there is no disruption at Northern Ireland ports. The grace periods for businesses moving goods between GB and NI are in operation and working well.
“We are aware of specific issues related to moving mixed food loads, known as groupage, and new guidance is coming soon following a successful trial with industry.”