An explosion in the Nigerian city of Yola has caused multiple deaths and injuries, with some reports saying more than 30 people may have died.

The blast appears to have struck a busy market area where traders were closing up for the day.

Nigerian President Muhammadu Buhari visited Yola on Saturday, declaring that the Islamist militant movement Boko Haram was close to defeat.

Yola has twice been hit by deadly bomb attacks this year.

The city lies in the north-eastern state of Adamawa, one of the worst hit by the Boko Haram insurgency.

Boko Haram at a glance

.Founded in 2002, initially focused on opposing Western-style education - Boko Haram means "Western education is forbidden" in the Hausa language

.Launched military operations in 2009

.Thousands killed, mostly in north-eastern Nigeria, hundreds abducted, including at least 200 schoolgirls

.Joined so-called Islamic State, now calls itself IS's "West African province"

.Seized large area in north-east, where it declared caliphate

.Regional force has retaken most territory this year