PARIS (Reuters) - A fourth French soldier deployed in an eight-week-old military campaign against Islamist rebels in Mali was killed on Wednesday, the French government said.

The soldier, a sergeant from the 68th African artillery regiment, was killed during an operation in eastern Mali around 100 km (60 miles) from the town of Gao, President Francois Hollande's office said in a statement.

Dozens of Islamist fighters linked to al Qaeda have been killed as French and African forces have fought to drive them out of the northern Malian region they have controlled since last April.

(Reporting by Jean-Baptiste Vey; Writing by Catherine Bremer; Editing by Robin Pomeroy)