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Sailings to the port of Dover were disrupted by a security alert on the other side of the Channel.
DFDS Seaways crossings had to temporarily be suspended after the incident in Calais.
According to the company's twitter feed some passengers who were due to travel on the 1225 sailing may have been stuck outside the French port.
Customers who were held at Border Control were told they would be transferred onto the next available crossing once services resumed.
Services have now started running again and passengers are being moved onto alternative sailings.