Many French bosses think the compulsory 35-hour week is having an adverse effect on the country's economy, according to new research.
Workers enjoy longer holidays but face restrictions on overtime
Of 1,000 heads of small firms polled by Ifop, 93% said they would like to see restrictions on staff work hours eased.
The 1999 law was intended to reduce France's high unemployment rate.
The survey's publication coincides with a staff vote at a Robert Bosch car parts factory where workers chose longer hours in order to save jobs.
The majority of the 820 workers at the Bosch factory in Venissieux, near Lyon, said they would rather work 36 hours without any financial compensation for the extra hour than see their plant relocated to the Czech Republic.
They also accepted a three-year pay freeze.
According to the company, the vote on Monday has given the factory a new lease of life.
"We don't plan to apply this measure to other sites in France," a spokesman told the French newspaper Les Echos.
"This accord is not a ... reference but a specific response to a
France's 35-hour working week is becoming a hotly-contested political issue.
French finance minister Nicolas Sarkozy said last month that the short working week was putting a huge strain on the nation's economy.
Sarkozy has spoken against the 35-hour week
He said the policy directly costs the French Government and firms 16bn euros (£10.6bn; $19bn) a year.
By restricting companies, he said the rule had left the French economy far less flexible than its competitors.
But some trade unions disagree.
While some union members backed the Bosch plant's decision on the grounds that it saved jobs, others rejected it, saying the move could spell the beginning of the end of the 35-hour week introduced by the socialist ex-prime minister Lionel Jospin.
"When the school year starts in September, we are going to
organise union actions to win back our rights," CGT union official Serge
Trucello told Reuters news agency.
United States 5.6%
"It (the vote at Venissieux) must not in any case be applied to
other Bosch plants in France," said leader of the CFE-CGC union Jacques Le Bars.
Many firms have moved their operations from Western Europe to Eastern Europe, where labour costs are cheaper.
In Germany, employees at two plants belonging to the engineering giant Siemens agreed to work 40 hours instead of 35, without extra pay, to prevent their jobs being relocated in Hungary.
Unions are presently locked in discussions with management at German car-maker DaimlerChrysler over longer working hours.
France's President Jacques Chirac has said the working time law should be relaxed, but must ultimately remain in force.
It is likely that any attempt to overturn the law would be met by huge protests.