Strikes by French and British workers on both sides of the Channel are likely to cause significant disruption on the May bank holiday weekend, travellers have been warned.

UK Border Force staff represented by civil service union PCS are walking out on Friday (April 28). The move is part of an on-going dispute about pay and conditions, which the Government says will cause delays for international arrivals at all UK airports and ports until at least 7am on April 29.

Action will also impact UK border controls in Calais, Dunkirk and Coquelles.

Meanwhile, in France, further demonstrations and wildcat strikes are predicted in a number of large cities as locals protest about the country’s controversial plan to raise the state retirement age.

In updated travel advice for France, the Foreign Office said that unions have announced “large-scale demonstrations and co-ordinated industrial action” on May 1, and that transport networks and roads travel could be disrupted.  It also warned strikes could begin earlier than expected.

“Industrial action may start the evening before the strike day and run for several days,” the alert stated. “You should monitor the media, check the latest advice with operators before travelling, avoid demonstrations and follow the advice of local authorities.”

Eurostar said passengers due to travel should check its website for updates regularly, along with the SNCF website if travelling to or from Lille or Paris.

At present, UK airports say there on no scheduled changes to inbound arrivals caused by the Border Force strike. Arriving passengers with biometric passports are advised to use e-gates to minimise their time in a queue.

However, later on in the week Heathrow is preparing for industrial action over pay by security officers. Staff represented by the Unite union will strike on May 4-6, and then again on May 9-10. The action will hit Terminal 5 and cargo control, and follows a similar 10-day strike in April.

A Heathrow spokesperson said: “We kept Heathrow running smoothly during the first 10 days of Unite’s failed industrial action, and passengers can have confidence that we will do so again this time. We will not let Unite disrupt the flow of visitors to the UK during such an important period for the country.”

To avoid crowds forming in the airport, Heathrow says travellers should arrive no more than two hours before short-haul flights, and three hours for long haul.

Meanwhile, Air Europa pilots have confirmed a four-day strike for May 1, 2, 4 and 5, which will hit hundreds of Spanish flights, including services to and from Gatwick, Aberdeen and Edinburgh.