The blast occurred near a hotel often used as a meeting place for local officials, witnesses said.

The Islamic State group has claimed its first suicide attack in Somalia that left five dead as it steps up activities in a region dominated by the a-Qaeda-linked Shabaab.

The group's self-styled news agency Amaq claimed the “martyrdom-seeking operation with an explosive vest” in a statement carried by the SITE Intelligence Group which noted it was the first suicide bombing by the militants in Somalia.

The suicide bomber detonated his explosives vest at a checkpoint in the northeastern port city of Bosaso late Tuesday, situated in the semi-autonomous region of Puntland.

“Security forces stopped the suspect when he approached but he detonated himself leaving five people dead. One of the security officers and four civilians were killed in the blast,” said local police official Mohamed Dahir Adan.

The blast occurred near a hotel often used as a meeting place for local officials, witnesses said.

"I think the bomber was trying to target the hotel but he was stopped at the checkpoint close to the hotel and he decided to detonate his explosives," said witness Awke Mohamed.

Puntland set up its own government in 1998, but unlike neighbouring Somaliland, it has not declared full independence.

The region has often come under attack by Al-Qaeda-linked Shabaab militants and is also home to a breakaway group of fighters who have declared allegiance to IS.

However the group has so far failed to gather much support while the Shabaab has taking pains to purge those expressing pro-IS sentiment from their ranks.

Shabaab the bigger threat

The militants are led by former Shabaab cleric Abdiqadir Mumin who switched allegiance from Al-Qaeda to IS in October 2015 and was named a "global terrorist" by the US State Department in August.

Aside from issuing occasional promotional videos, the group seized the small fishing town of Qandala before being ousted by Puntland forces in December.

Then in February IS claimed an attack by gunmen on a hotel in Bosaso which left four security guards dead.

Rashid Abdi of the International Crisis Group, said that while Mumin's group was stepping up its activities, the Shabaab remained the biggest threat in the region.

“We should not overplay IS influence in that region,” he told AFP.

“There is clearly an IS threat in Puntland, and the Mumin group is escalating its activities and attacks, but Al-Shabaab remains a much bigger threat in Puntland than IS does.”

He also warned that IS claims should be treated with caution as "they tend to claim everything".

IS leader a British cleric

Mumin was born in Puntland and lived in Sweden before moving to the UK in the 2000s, where he was granted British citizenship.

In London and Leicester, he developed a reputation as a firebrand preacher at extremist mosques and in videos posted online.

Monitored by MI5, Britain's domestic intelligence agency, Mumin is thought to have known Mohamed Emwazi, the IS executioner nicknamed 'Jihadi John', and Michael Adebolajo, one of two people convicted over the 2013 murder of British soldier Lee Rigby in London.

In 2010, Mumin travelled to Somalia to join the Shabaab — which both Emwazi and Adebolajo had unsuccessfully tried to do.

He initially served as an imam and propagandist before taking control of the Puntland faction of the Shabaab and later defecting to IS with a handful of fighters — despite lacking battlefield experience.

Observers say his supporters are mostly made up of members of his own Majerteen clan, and the very existence of Mumin's group is attributed to complex local clan rivalries.

The International Crisis Group estimated in November that his group counted some 200 members and warned the threat of IS could not be “dismissed as insignificant”.

The group called for a “genuine political initiative to address local clan grievances”.