A suicide bomber on Sunday detonated his explosives among policemen standing in line outside a police base in the southern Yemeni city of Mukalla, killing 25, security and health officials say.

They said at least 17 more people were injured in the attack.

The Yemeni affiliate of the extremist Islamist State group claimed responsibility for the attack in a statement posted on social media networks by sympathizers with the group.

Sunday's victims were policemen returning to work for the first time since last month's recapture of Mukalla by forces of the internationally recognized government. The port city had been held for more than a year by Yemen's local al-Qaida affiliate.

The victims also included young men applying for jobs with the city's local police, according to the officials, who spoke on condition of anonymity because they were not authorized to speak to the media.