A convoy carrying Borno state governor Babagana Zulum came under fire from militants this week, forcing him to cut short a trip to the northern town of Malam Fatori, three military sources and a security source told Reuters on Saturday.

The attack, which raises questions about the governor's pledge to close displaced persons camps and send those in them back to their villages, took place on Thursday, the sources said.

"Troops battled for nearly an hour," one military source said, adding that all those in the convoy laid on the ground during the fighting.

Malam Fatori sits near the border with neighbouring Niger.

Spokespeople for Zulum and for the military did not respond to requests for comment.

Zulum said earlier this month that he would shut the camps that hold thousands of internally displaced persons in the state capital, Maiduguri, by the end of the year, citing improved security.

Borno state is the centre of Nigeria's 12-year battle against Islamist insurgents, including Boko Haram and Islamic State West Africa Province. The fighting has killed nearly 350,000 people and displaced millions more, according to United Nations Development Programme estimates. (Text, excluding headline: Reuters)

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