BAMAKO, Oct 6 (Reuters) - Islamist militants killed at least nine soldiers and wounded at least 11 more in central Mali on Wednesday, the army said, while local officials said the death toll was even higher. The attack involving an improvised explosive device occurred between the towns of Koro and Bandiagra in the Mopti region, an epicentre of violence in Mali by insurgents linked to al Qaeda and Islamic State, the army said in a statement. The soldiers returned fire, killing 15 militants, it said, adding that the death tolls on both sides were provisional. Moulaye Guindo, the mayor of the nearby town of Bankass, said 16 soldiers had been killed, while another local official, who asked not be named, said more than 10 soldiers had died. Malian soldiers as well as French counter-insurgency forces that support them and United Nations peacekeepers are frequently targeted in central and northern Mali by the militants. Fifteen Malian soldiers were killed in the centre of the West African country in August when their convoy was ambushed. A French serviceman was also killed last month in a clash with a militant group near Mali"s border with Burkina Faso. read more Reporting by Tiemoko Diallo and Paul Lorgerie Editing by Mark Heinrich and Alistair Bell