THE prospect of World Cup fans being stranded - and even missing games - has soared as French unions yesterday held to ransom their government as well as employers.

Air France pilots underlined the potential for massive transport disruption, leaving thousands of passengers without flights across the country.

Their strike coincided with train drivers repeating threats of walk-outs during the middle of first round matches and calling for a 36-hour stoppage from Friday.

If confirmed, thousands of supporters due to flood Paris at the weekend for the opening game between Scotland and Brazil next Wednesday will suffer.

In addition, lorry drivers yesterday refused to rule out World Cup blockades, regardless of their leaders' promises not to upset fans by paralysing the tournament. Troubles may also loom for supporters travelling by ferry.

Air France pilots yesterday launched a four-day strike to block wage cuts, and raised the spectre of similar actions during the tournament. The official carrier for World Cup teams expected to carry 100,000 passengers yesterday, but had to cancel nine out of every 10 long-haul flights and almost 75% of domestic services.

Foreign airlines were not affected, but there are fears that knock-on effects will prove inevitable as Air France pilots review their position every four days and strikes are repeated over the next fortnight at least.

With games being played in 10 different stadiums around the country, supporters face being stranded at airports, or finding other means of transport.

Train drivers have already threatened to strike on June 16, 17, and 18 - which includes Scotland v Norway, in Bordeaux - and yesterday increased pressure on the embarrassed left-wing government of Prime Minister Lionel Jospin by signalling a 36-hour walk-out from Friday.

The state-owned airline strike began at midnight after failures to reach agreement. In contrast to past conflicts, when ground crews blocked runways, about 98% of Air France's 3200 pilots kept a low profile by not showing up for work.

A spokesman for SNPL, the union leading the strike, admitted the consequences for passengers were ''disastrous,'' but added: ''We have no other choice . . . when you're confronted by an attack, you have no choice but to defend yourself.''

However, frustrated passengers, trying to switch tickets to other carriers, condemned the pilots.

One said: ''They use an international event to bother everyone, it's too bad. That's not the image of France, it should be avoided.''

Transport Minister Jean-Claude Gayssot urged both sides to ''take up the path of discussion'', but one French MP, George Sarre, fearful the country's image will be damaged during the tournament, denounced the pilots as ''the damned of the earth''.

Among the highest paid in the world, the pilots want Air France to abandon plans to save #51m a year by cutting salaries by 15%.

Air France president Jean-Cyril Spinetta defended the bid to pay pilots hired after June 1997 a lower salary than predecessors. He said it was ''critical'' to keeping the airline profitable on returning to profit after seven years in the red.

Other transport disruptions for the 2.5m fans expected in France include:

Rail: employees want increased salaries; 20,000 extra workers, and the immediate introduction of a 35-hour working week.

A spokesman for the Communist-led GCT union said: ''No-one wants the World Cup to be disrupted by industrial action, but . . . no-one can guarantee that there won't be a reason to strike.''

Roads: lorry drivers want basic wages raised from #4.30 to #5.60 an hour.

After a brief stoppage in support of their campaign for better pay and working hours last week, Mr Roger Poletti, head of the transport section of Workers Force, pledged a trouble-free World Cup and not to block roads around World Cup grounds.

However, past experience suggests haulage unions are unable to control their militant members. Meanwhile, farmers - who can also paralyse roads - remain an unknown factor, and may well add to the chaos.

Sea: French ferry workers fear job losses if the EU abolition of duty free goes ahead. They are also disgruntled over a directive liberalising the hiring of seamen, arguing it favours EU states where wages are lower.

Any action to blockade ports is likely at the start of the tournament.

Industry: Will slow down on Friday, with GCT calling for a strike expected to affect most public services and energy and construction sectors. Teachers, shop workers, the unemployed, and immigrants are also planning nationwide protests during the tournament.

Even French police are threatening to strike, seeking a pay rise for officers stationed outside the Stade de France where the opening ceremony, final, and seven other matches will take place.