The figure at 5.00pm local time on Sunday was lower than the 48.31 percent at the same time in the 2012 first round and much lower than in the first round of April's presidential poll.
That is a bad sign for turnout for the whole day - that was 57.22 percent in 2012 and 77.7 percent in April.
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Figures for turnout at noon showed Paris and the surrounding region particularly lacking in motivation with only 11.68 percent of voters casting their ballots in the capital, compared to 13.64 percent five years ago, and only 10.50 percent in nearby Seine-Saint-Denis.
Abstention was also high in French overseas territories, which have already finished voting.
In the Caribbean island of Guadeloupe it stood at 70 percent for the whole day.
There was a record abstention rate of over 60 percent on the Pacific archipelago of New Caledonia.
The abstention rate in French parliamentary elections has been rising over the years, from 22.8 percent in the first round in 1958 to 42.78 percent in the 2012 first round.
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