The 1977 law, which prohibited indications of results from being published until after the polls closed at 8pm last Sunday and can mean a $75,000 for errant editors, meant a dearth of up-to-the-minute information was available on France's own news sites, despite a clamour to find out more online.
European web traffic monitor XiTi reported a rush of visitors to French news websites long before the deadline, with as many as three times the regular number of visitors.
"From 2pm, the visits grow, whereas on the preceding Sunday, visits stagnated in the afternoon," a spokesperson said. "The progression of the visits are strongly emphasised starting at 5pm and reach a veritable peak from 6pm to 8pm.
"The internet users visibly searched for information concerning the first estimates of the first-round election results before the official announcement at 8pm on the television networks. This would explain the peak of visits between 6pm and 8pm, then a fall starting from the moment where the results were televised."
Information-hungry French voters were forced to turn to news sites in Switzerland, Belgium and the UK, unrestricted by their domestic election laws, for early exit polls.
"Some estimates popped up on the web two hours before polls closed, when thousands of voters were still waiting in line," reported Associated Press' Paris correspondent, adding that some overseas sites that published the early returns were forced to post messages saying they were bogged down by unusually heavy traffic.
Even France's notoriously active bloggers, who complained foreign media had an unfair advantage, refrained from republishing exits from overseas for fear of attracting fines, said Alain Fichelle, head administrator at the Presidential Election Commission.
Reporting of exit polls has previously caused controversy in the US, where the 2000 presidential election sparked complaints news organisations used flawed data to declare a winner too soon.
In France, the head-to-head run-off between centre-right candidate Nicolas Sarkozy and Socialist Segolene Royal takes place this Sunday, 6 May.
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