Three coordinated Islamic State group bomb attacks on Yemeni government forces killed 38 people in the southern port city of Mukalla on Monday, medics and security sources said.

They said 24 other people were wounded in the bombings, which occurred just as soldiers were about to break their daylong fast during the Muslim holy month of Ramadan.

Islamic State group militants claimed responsibility for the attack via their online news agency, Amaq.

Praying in Sanaa People perform the Alasr prayers during the holy month of Ramadan at a mosque in Yemen's capital, Sanaa, June 24, 2016. Photo: REUTERS/Mohamed al-Sayaghi

The first explosion occurred as an attacker detonated his suicide vest at a checkpoint on Mukalla's western approaches.

A second blast came from a bomb-laden car at the military intelligence headquarters, and the last was an improvised explosive device that went off as soldiers were about to begin their evening meal.

Mukalla, capital of the vast eastern province of Hadramout and an important shipping hub, was the center of a wealthy mini-state that al Qaeda in the Arabian Peninsula (AQAP) built up over the past year as it took control of an almost 600-km (370-mile) band of Arabian Sea coastline.

In late April, Yemeni and Emirati soldiers wrested back Mukalla from AQAP, which put up little resistance before withdrawing its forces.

The Islamic State group's Yemen branch carried out a suicide bombing in the southern port city of Aden on May 23 that killed 40 army recruits, the latest in a string of attacks claimed by the group also known as ISIS.

Islamist militants have gained territory and freedom to operate thanks to a war raging for over a year in which government forces have been pitted against Iran-allied Houthi rebels who control the capital, Sanaa.

Yemeni security officials believe there is an overlap between adherents of al Qaeda and ISIS, though the two groups are ideological rivals and compete for recruits.

"Sleeper cells still exist in Mukalla and we are working against them every day," a security official said.

"Since the liberation of the city, security forces have arrested hundreds of al Qaeda fighters in raids, uncovered plots and seized around 20 explosive cars."