Japanese carmaker Honda has warned that production at its Swindon plant may be disrupted, because transport problems may cause a shortage of parts.
The plant operates on a "just in time" production system, where parts arrive at the factory when they are needed.
Honda has told employees that it is currently experiencing vessel delays and congestion at UK ports.
It is looking at other arrangements, such as air freight, but disruption could begin as early as Wednesday.
Congestion at UK container ports has been building up in recent weeks, causing problems initially at Felixstowe, but recently at Southampton and London Gateway as well.
The backlog has built up as companies increased orders after the initial pandemic lockdown, while some have looked to stockpile goods before the end of the Brexit transition period.
Congestion at England's ports is now so bad that some shipping firms have limited the amount of cargo they will bring to the UK.
Consignments have reportedly been offloaded at continental ports such as Antwerp, Rotterdam and Zeebrugge.
In a statement, Honda said: "Due to transport-related delays, potential parts shortages may interrupt production.
"Whilst a number of measures are being taken to mitigate any disruption, there could be a temporary pause to production to enable any supply issue to be resolved."
Honda is looking at air freight to ease its supply problems . The chances are other businesses may have to do the same.