Eurostar insists it will be "business as usual"

The company insists the walkout over pay by customer service staff will have "no impact on passengers or services".

But the RMT union says the strike will slow down the processing of the 14,000 people expected to use London to Paris and Brussels services this weekend.

Elsewhere, engineering works threaten to cause motorway and rail delays.

Eurostar ticketing and platform staff are going on strike over pay and grades at London Waterloo and Ashford, in Kent.

The RMT has warned that more of its members at Eurostar could get involved in the dispute in the future.

The company is running extra eight trains to cope with demand for London to Paris and Brussels services this weekend, with 140,000 customers due to travel.

1 Great Western Mainline closed Paddington - Reading M25 has 40mph limit junctions 12-15 near Heathrow 2 & 3 West Coast Mainline closed Hemel Hempstead - Lichfield and Stockport - Manchester 4 Link roads to M6 spaghetti junction closed Eurostar - strike but no delays expected by company Airports - busy but no specific delays expected TUC calls for extra bank holidays

Eurostar communications director Paul Charles claimed the RMT was using the Bank Holiday period to cause maximum disruption.

"Travellers are fed up with the RMT's attempts to disrupt their holiday plans," he said.

RMT general secretary Bob Crow said: "Unequal and unfair pay have no place in any modern transport system, and our members have made it clear they will no longer tolerate it."

Elsewhere, engineering works are expected to cause disruption on two motorways, the M25 and M6, and on several train routes.

Although some roadworks are being lifted for the weekend, motorists are facing 40mph speed restrictions on the M25 near Heathrow airport, while a number of link roads to the Spaghetti Junction on the M6, leading to Birmingham, will stay closed.

'Plan ahead'

An AA spokeswoman said: "We expect people to make the most of the last bank holiday before Christmas and the level of disruption will depend on the weather."

The Highways Agency's chief executive, Archie Robertson, urged drivers to plan their routes in advance and listen to travel bulletins to check latest conditions.

For travellers heading abroad, British Airways - which cancelled six domestic flights on Friday after suffering staff shortages and technical problems - said it was impossible to predict what would happen over the weekend.

The company's chief executive Rod Eddington and 11 other directors have been drafted in to work at Heathrow during the break.

Much of the West Coast main line - Hemel Hempstead to Lichfield and Manchester to Stockport - will be shut for major engineering works.

The Great Western Mainline will also close between London Paddington and Reading, Berkshire.