The French are no strangers to strikes
This raises the spectre of chaos when euro notes and coins are launched a day earlier.
"We are heading for a strike," a senior official from the Force Ouvriere union - which comprises about 30% of France's banking work force - told BBC News Online.
A wider strike of up to 400,000 bank employees is "a strong likelihood coming out of inter-union talks," taking place this afternoon, he added.
Five main unions representing bank workers have reiterated their "intention to unleash a massive professional strike if management intransigence persists".
France's finance minister, Laurent Fabius, said he hoped "reason would prevail", given the euro transition's status as a "historic act".
"It would be paradoxical to begin this period" with the banks closed, he said.
Compensation demands
French bank clerks are demanding more compensation for the extra work relating to the currency changeover.
The unions are demanding increased security, more pay and better training in order to deal with the introduction of euro cash.
They say a number of private banks are refusing to abide by a deal struck in July over the issue.
The future of the Bank of France once the euro is launched is also a contentious issue.
Euro notes and coins will go into circulation in the 12 countries that belong to the eurozone on 1 January.
Escalating strikes
Till they relented today, workers at the country's only production site for notes and coins near the southwestern city of Bordeaux had been striking since 15 November.
Mr Fabius sent riot police in two days ago to prevent picket lines from halting delivery trucks taking coins to and from the Mint.
Meanwhile, unions for Paris postal workers said on Wednesday they would strike on 14 December, when kits of euro coins are to be made available to the public two weeks ahead of the official launch.