A Boko Haram attack in the Nigerian city of Maiduguri killed at least 15 people and wounded 83, a military spokesman said on Monday in the biggest strike since the government said it was in talks with the Islamist militant group.

The military said the incident occurred late on Sunday  and included gun battles between government troops and the militants as they tried to enter Maiduguri, a city in northeast Nigeria which is the epicentre of a nine-year conflict with Boko Harm that has caused the deaths of more than 20,000 people.

The military said troops clashed with the jihadists in a cashew plantation around Bille Shuwa and Alikaranti villages, near Giwa barracks on the edge of Maiduguri’s inner city, at around 08:10 p.m. on Sunday and fought gun battles with government troops during which multiple blasts were heard.

In early 2015 Boko Haram controlled a swathe of land in northeast Nigeria around the size of Belgium but was forced out of most of that territory by the army with the support of troops from neighbouring countries. Since then the group has continued to carry out suicide bombings, gun raids and kidnappings in northeastern Nigeria as well as in neighbouring Cameroon, Niger and Chad.