US activist investor Guy Wyser-Pratte is turning the heat up under Lagardère and claims to have new evidence proving that last summer's board seat bid was hit by flawed voting procedures.

At stake is Wyser-Pratte's attempt to shake up management and strategy at the publishing group whose share ownership structure gives CEO Arnaud Lagardère control over the group while owning less than 10 per cent of the share capital.

Speaking to the Financial Times, Wyser-Pratte said that he has written to the AMF, the French stock market regulator, claiming that errors in the final vote count of  independent minority US shareholders meant he ended up with only 22% of the vote, roughly half what he asserts is the correct tally.

“I was clearly short-changed,” said Wyser-Pratte, “There is a high probability I would have won the vote.”

This is the second time that Wyser-Pratte has raised the issue with the French authorities. In June 2010 he wrote to the AMF asking for an investigation in the vote count which the regulator subsequently claimed to be "satisfactory".

The extent of the new evidence on the vote discrepancy is unclear, however Wyser-Pratte is determined to get an answer. “The authorities owe it to shareholders to provide accountability,” Mr Wyser-Pratte told the Financial Times. “A vote is a valuable thing. What does it mean for Paris as a place to invest if they’re that cavalier about people’s votes?”