The first ferry from Britain bound for Calais after the UK's exit from the EU customs union docked in the northern French port on Friday, with three dozen vehicles disembarking in a smooth operation, an AFP correspondent said.

The Pride of Kent of P&O Ferries docked in Calais at 0915 GMT, hours after Britain left the customs union and single market in the final act of Brexit.

There had been no ferries earlier in the day due to the New Year.

Under the rules of the so-called "smart border" implemented by French authorities to minimise queues, hauliers send information on their freight in advance with disembarking traffic either waved through or told to stop for further checks.

Of the 36 trucks disembarking from the Pride of Kent, which left from the British port of Dover, three were told to stop for additional checks, the AFP correspondent said.

Calais port president Jean-Marc Puissesseau said Thursday that officials were relaxed about the new arrangements after carrying out dry runs and investing 13 million euros ($15.6 million).

Some 70 percent of trade between Britain and the EU passes through the French ports of Calais and Dunkirk. On average, 60,000 passengers and 12,000 trucks pass through daily.

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