The British ports sector is on edge over Parliament's rejection of Prime Minister Theresa May's Brexit deal, fearing the departure will take effect in 73 days without an accord in place.

"The ports industry notes developments in Parliament this evening and some in our sector will have real concern about the increasing possibility of a ‘no deal’ Brexit outcome," British Ports Association chief executive Richard Ballantyne said.

"We would urge the government to clarify its alternative plans immediately and do whatever is necessary to avoid a disorderly withdrawal from the EU."

Parliament rejected May's plan with a 432-202 vote, marking the biggest defeat in the House of Commons for a prime minister in recent British history, the New York Times reports.

Ballantyne said the ports association discussed the fallout of a "no-deal" Brexit with ministers for more than two years and knows they are aware the havoc this would cause at key ports.

"Whilst plans are in place to mitigate some of the worst aspects of this, the fundamental dangers to free flowing trade remain and must be avoided if at all possible," he said.

Ports also have a vested interest in a stable and healthy economy. We are obviously now very close to exit day and many in the ports sector will be seeking guarantees that time will found for further negotiation to avoid the UK leaving the EU on unfavourable terms."

Stocks not shaken by Brexit news

In US markets, shipping stocks appeared to take the late-in-the-trading-day Brexit news in stride.

Among the stocks with the biggest gains Monday, Seacor Marine Holdings jumped 5.1% to $14.01, while Carnival shares reached $52.92, up 1.38%, to the good.

Among the losers, Eagle Bulk Shipping shares dipped 5.18% to $4.76. GasLog dropped 1.55% to $17.81.