BBC: France's national rail workers have begun an open-ended strike called in protest at President Nicolas Sarkozy's planned pension reforms.
Rail employees stopped work at 2000 (1900 GMT) and thousands of commuters will be affected on Wednesday morning.
Utility workers are also set to strike. They may be joined by teachers and civil servants on 20 November.
Eurostar says the first train services from London's new St Pancras terminal will be unaffected by the action.
The next few days will be a real test of the French prime minister's nerve, reports the BBC's Emma Jane Kirby from Paris.
"Tomorrow is going to be a hellish day for travellers and perhaps for many days beyond that," Labour Minister Xavier Betrand warned on Tuesday.
That view was echoed by Prime Minister Francois Fillon who told parliament: "Millions of French people will be deprived of their fundamental freedom, the freedom of movement and even perhaps to work." French unions strike over reforms (more)
Mark Alexander
