MAIDUGURI, Nigeria (Reuters) - Suspected Islamist militants killed at least 11 people in northeastern Nigeria in an attack on a security convoy that was taking people displaced by an insurgency back to their homes, police and security sources said on Saturday. Islamic State, to whom a breakaway faction of Nigerian militant group Boko Haram pledged allegiance in 2016, said on its Amaq news agency that 30 police officers and soldiers were killed in the attack on Friday on a road leading to the strategic fishing town of Baga in Borno state. In a statement on Saturday, Borno state police said eight police officers and three members of a government-approved militia were killed, and 13 people were wounded in the attack around noon (1100 GMT) on Friday. Two soldiers, a police officer and a member of the government-approved militia - all speaking anonymously because they were not authorised to speak to journalists - told Reuters at least four soldiers were also killed. Two Nigerian military spokesmen did not immediately respond to requests for comment. President Muhammadu Buhari “urges security and intelligence agencies to intensify efforts to check sabotage, sanitize the roads, venues and locations well in advance of returning IDPs (internally displaced people)”, a statement issued by his spokesman said. Islamist militants have forced more than 2 million people to flee their homes since 2009 when Boko Haram began an insurgency aimed at creating a state adhering to a strict interpretation of sharia law. Some 30,000 people have been killed in the conflict. The convoy was taking people back to Baga at the start of an initiative by authorities in Borno to relocate displaced persons to their homes. Borno is the insurgency’s birthplace and the state worst hit by the conflict. Islamic State’s West Africa Province (ISWAP) has become a dominant force in the region in recent years, targeting attacks on security forces. Boko Haram has carried out suicide bomb attacks and shooting raids on residents.