ADEN (Reuters) - A suicide bomber killed at least four people on Tuesday in an explosion in the southern Yemeni port of Aden targeting young army recruits, witnesses and a security source said, the second attack of its kind in two months.

Islamic State claimed responsibility for the attack, which comes as a shaky U.N.-sponsored truce between the government of President Abd-Rabbu Mansour Hadi and its foes, the Iran-allied Houthis, held for a second day despite accusations of violations by both sides.

The witnesses and security source said a suicide bomber wearing an explosives-laden belt had blown himself up amid young army recruits waiting for buses in the north of the city.

Islamic State’s Yemen wing said in a statement on its Amaq news website that it had detonated an explosives device against government soldiers killing five and wounding seven others.

Islamist militants have exploited Yemen’s year-old civil war to increase their presence and carry out a series of deadly attacks against troops loyal to Hadi and his backers from the Saudi-led alliance in southern Yemen.

In February, a suicide bomber killed at least 13 recruits at an army camp run by Hadi’s government in Aden.

The truce now underway is meant to pave the way for peace talks next week in Kuwait. Islamist militant groups such as Islamic State and Al Qaeda in the Arabian Peninsula are not party to the truce.