An Islamic State militant rammed an explosives-laden car into an army recruiting centre in Aden on Monday, killing 71 people, in the deadliest jihadi attack on the Yemeni city for more than a year.
Security officials said the attacker drove through a gate that had been opened for a delivery vehicle, and into a gathering of recruits.
Witnesses said some recruits were buried under rubble when a roof collapsed after the blast. Medical sources could not immediately verify whether all those killed in the attack were army recruits.
Doctors Without Borders (MSF) said its hospital in Aden had received 45 dead and at least 60 wounded following the explosion.
Isis claimed responsibility for the bombing on its official propaganda outlet.
Aden is the temporary base of Yemen’s internationally recognised government, which was forced into exile after Iran-backed insurgents seized Sana’a and other parts of the country.
The city has experienced a wave of bombings and shootings targeting officials and security forces. The attacks are often claimed by jihadis from either al-Qaida or Isis, which have both taken advantage of the chaos in Yemen to make gains in the south and south-east.
The Yemeni army, supported by a Saudi-led coalition, is training young recruits to join its nationwide war against Shia Houthi rebels and their allies, as well as Sunni jihadis.
This month a suicide bomber drove a vehicle into a large group of army reinforcements sent from Aden to fight jihadis in neighbouring Lahj, killing five soldiers. No group has claimed that attack.
On 20 July four policemen were killed in a bomb attack in Aden that was claimed by Isis. In May twin suicide bombings in Aden claimed by Isis killed at least 41 people.
This month government forces backed by a Saudi-led coalition entered Zinjibar, the capital of Abyan province. Troops have retaken other towns across Abyan but have been met by fierce resistance in the key al-Qaida stronghold of al-Mahfid, security sources said.
The militants still have a presence in areas surrounding the recaptured towns and control large parts of neighbouring Shabwa province, the sources say.
An Arab coalition battling the rebels and their allies in Yemen has been providing troops with air cover throughout their war against the jihadis. The US has carried out numerous drone strikes against al-Qaida in the Arabian Peninsula (AQAP) operatives in Yemen.
The Saudi-led coalition intervened in Yemen in March last year and has helped government forces push the rebels out of Aden and four other southern provinces since July 2015.
The war in Yemen has affected security in Saudi Arabia, where shelling from Yemen killed three Saudi children and wounded nine other people on Sunday.
Cross-border attacks from Yemen have intensified since the suspension in early August of UN-brokered peace talks between the rebels and the Saudi-backed government.
The Arab coalition has stepped up its air raids in Yemen since peace talks collapsed. On Monday a coalition airstrike north of Sana’a killed eight civilians including a child, rescuers and witnesses said.
More than 6,600 people, mostly civilians, have been killed in Yemen since March 2015 and more than 80% of the population has been left needing humanitarian aid, the UN says.
A plane chartered by the International Committee of the Red Cross (ICRC) landed at Sana’a airport on Monday carrying insulin for thousands of people suffering from diabetes.