A suspected Boko Haram bomb blast has killed at least 15 people and wounded 21 in the north-eastern city of Gombe, an emergency services official confirmed.

No group has yet claimed responsibility for the attack but suspicion will fall on the Islamist militant group as it continues to wage an insurgency in the country's north-eastern states.

An official from the National Emergency Management Agency (Nema) told Reuters on condition of anonymity those wounded in the blast were being treated and it was unclear whether the explosion was caused by a suicide bomber.

The attacks represents the second on the city's public transport network since October after a car bomb at a bus stop killed at least 10 people.

The terror group have carried out a wave of attacks in northern Nigeria in their quest to establish an Islamic caliphate in similar fashion to that of the Islamic State [IS] in Iraq and Syria.

According to Human Rights Watch, the militants have killed at least 2,053 people since the beginning of 2014, but researchers at the John Hopkins University School of International Studies estimate that 7,000 people have been killed in the 12 months between July 2013 and June this year.