Nigeria's President Muhammadu Buhari has taken to Twitter to reassure citizens that the country will soon be free from terrorism. The president made the promise hours after more than 30 people were killed and 80 injured in Yola, capital of Adamawa state, after attacks blamed on terror group Boko Haram.

Although Boko Haram has not claimed responsibility for the bomb blast at a vegetable market in Yola, the attack bears the hallmarks of the Islamist group, which has killed between 17,000 and 20,000 people since its insurgency became violent in 2009.

The group directs its attacks at three states in Nigeria - Adamawa, Yobe and Borno - and northern Cameroon, with coordinated bombings also occurring in other parts of Nigeria as well as Chad and Niger. In recent months, Chad and Niger have declared a state of emergency in areas affected by Boko Haram attacks.

When Buhari took office in May, he vowed his administration would end terrorism in the country. The former military leader relocated the military headquarters from the federal capital Abuja to Maiduguri - epicentre of Boko Haram's insurgency and the group's birthplace - and announced that a new Nigeria-led task force – consisting of 8,700 troops from Nigeria, Niger, Chad, Cameroon and Benin – was ready to take over in the ongoing regional fight against the terrorists.

Who are Nigeria's Boko Haram terrorists?

Boko Haram (recently renamed Iswap) fights against Western influence in Nigeria and aims to impose its version of Sharia law in the country.

The group declared an Islamic caliphate in Gwoza, along the Cameroon border, in August 2014.

Boko Haram has raided several cities in the north of the country in a bid to take control of more territory. Three states − Adamawa, Borno and Yobe − have been under a state of emergency since May 2013, due to Boko Haram's attacks.

The Nigerian government declared that the militants have been surrendering but the group has refuted the claims in an audio message. The voice identified in the broadcast is thought to belong to Boko Haram leader, Abubakar Shekau, who was rumoured to have been replaced due to his prolonged absence from the group's videos.

Some analysts have criticised Buhari after backing the military to defeat Boko Haram by November, a deadline subsequently moved to December. He argued more time was needed to defeat the group, deemed the world's deadliest terror group on the eve of the Yola attack.

More than 1,000 people have now been killed since Buhari assumed office with Boko Haram also claiming responsibility for an attack that left at least 18 people dead in Abuja in October.

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