Any introduction of tariffs, quotas and new customs clearances at UK ports after the UK leaves the EU could cause “significant difficulties” for the supply chain, an influential group of MPs have been told.

Montrose Port Authority chief executive Nicholas Scott-Gray warned the All-Party Parliamentary Group on Freight Transport (APPG) that if Brexit is wrongly handled, businesses dependant on imports and exports out of UK ports – including road hauliers – risked disaster.

“Tariffs, quotas and customs clearance regulations could cause significant difficulties,” he told the APPG, “if we slow down customers will go somewhere else.”

APPG chairman Rob Flello MP said in response to Scott-Gray: “If Brexit means increased friction at our ports, much of that trade will go elsewhere. There will be implications for everyone in the country, not just in terms of the products we buy but also for all those businesses that rely on raw materials and finished goods coming in and out.”

Flello added the government “has to be aware” of how vital to Brexit negotiations it was to keep ports moving as smoothly as possible.

“Any added delays as a result of our leaving the EU could be catastrophic. One would hope the government is collating a list of the key priorities for the negotiations, and the viability of our ports is right there near the top of page one,” he said.

The warning comes after the International Trade Committee warned that the cross-border movement of goods is “entering uncharted waters” as the government prepares for two years of Article 50 negotiations.