A suicide bomber killed at least 49 soldiers gathered to receive their monthly pay in the southern Yemeni port city of Aden, officials said, as the so-called Islamic State claimed responsibility for the attack.
Officials said at least 60 other troops were wounded in the attack, which occurred near al-Sawlaban military base in Aden's Khor Maksar district, where another IS suicide bomber blew himself up a week ago killing 50 soldiers.
The attacker immersed himself among the soldiers at Al-Sawlaba base, in Al-Arish district, a military official said.
In a statement posted via its Amaq news agency, IS said the attacker detonated an explosive vest amid a crowd of soldiers.
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Yemeni authorities have for months pressed a campaign against jihadists who remain active in the south and east of the war-torn country.
IS and its jihadist rival Al-Qaeda have taken advantage of a conflict between the government and Yemen's Huthi rebels, who control the capital Sanaa, to bolster their presence across much of the south.
The two extremist groups have carried out a spate of attacks in Aden, Yemen's second city and headquarters of the internationally recognised government whose forces retook the port from the Huthis last year.
But Al-Qaeda has distanced itself from the December 10 attack, claiming that it tends to avoids "the shedding of any Muslim blood" while focusing on fighting the "Americans and their allies."
Al-Qaeda has long been the dominant jihadist force in Yemen, located next to oil-flush Saudi Arabia and key shipping lanes, but experts say IS is seeking to supplant its extremist rival.
In August an IS militant rammed his explosives-laden car into an army recruiting centre in Aden, killing 71 people in the deadliest jihadist attack on the city in over a year.
A Saudi-led coalition has since March 2015 supported loyalist forces fighting the Huthis.
The Arab coalition intervened after Huthi rebels allied with troops loyal to Yemen's former president Ali Abdullah Saleh seized the capital Sanaa and overran other parts of the country.
The Yemen war has killed more than 7,000 people, about half of them civilians.