French drugmaker Sanofi, the country's largest firm by market capitalization, said Wednesday it would not continue its cooperation with CEO Christopher Viehbacher.

The 54-year-old with German and Canadian roots had been at the helm of the firm since 2008, overseeing its large-scale restructuring.

But Sanofi's board sacked him amid criticism of his leaving for Boston in the US to run the pharmaceutical group. He was also unpopular for pushing restructuring measures that could have led to massive job cuts.

Internally, he was known as the "smiling killer," according to the Reuters news agency.

Confidence-building measure

Sanofi announced the head of its administrative board, Serge Weinberg, would temporarily take over the role of CEO until a new boss was appointed.

"The company said it needed a manager who could "focus more broadly on execution with a close and confident cooperation with the board."

Shares in the drugmaker fell by more than five percent on the news in early trading on the Paris Stock Exchange. The renewed drop came after the stock dipped by 10 percent a day earlier over a disappointing earnings report.

Sanofi had reported a 2.4-percent profit slump in the third quarter amid restructuring costs and tax charges, but insisted its main treatments were doing well and research for new drugs, including a dengue fever vaccine, looked promising for the months ahead.

hg/ng (AFP, Reuters,dpa)