Yemen’s Iran-backed Houthi rebels claimed responsibility for an attack on a military parade in the government-held port city of Aden on Thursday.
The attack on Al Jalaa military camp in west Aden killed at least 30 officers, military officials said.
The camp is supported by the Arab Coalition that intervened on behalf of the the internationally recognised government of President Abdrabu Mansur Hadi.
The Houthis' Al Masirah TV claimed the attack was carried out with a drone and a ballistic missile. The rebel channel claimed the drone was a Qasef-2K, a variant of an Iranian-made model.
But Yemeni military sources said only a missile was used.
“The missile exploded in the courtyard of the military base resulting in the death of more than 30 officers. The attack was not conducted by a drone," a military source said.
Brig Gen Munir Al Yafaei, who is known as Abu Al Yamamah, was killed in the attack. He was one of the most prominent military commanders in southern Yemen.
"The general was on a podium standing next to other military officials when the attack took place. The rocket fell directly on him," the official said.
The missile left a large crater in the grounds of the military compound.
Aden is home to Yemen's government in exile since Houthi rebels seized the capital Sanaa in 2014.
Yemen's government denounced the attack.
"The heinous and simultaneous targeting by Houthi rebels and terrorist groups on the security and stability of Aden evidently shows a co-ordination under a clear Iranian directive," said Maeen Saeed, the Yemeni Prime Minister.
"Yemen will persevere nevertheless. We shall stand strong."
Earlier on Thursday, a suicide bomber attacked a police station in the Sheikh Othman neighbourhood of Aden.
Three officers were killed and more than 20 people wounded, including civilians, when the attacker detonated his device as policemen were arriving for the start of their shifts.
Medical officials expected the death toll to rise.
"Tens of wounded were hospitalised to Aden surgical hospital after an explosion in the surrounding area," Doctors without Borders said on Twitter.
No group has claimed responsibility for the earlier attack.
Mr Hadi said the attacks showed the rebels' “unwillingness to find peace".
“What happened today has made it imperative for our forces to confront the rebels, to stop their acts and to liberate our country,” he said.
Saudi Arabia’s envoy to Yemen accused Iran of being behind the attacks.
"The attacks on the stability of Aden by the rebels and sister groups such as ISIS and Al Qaeda proves their aim to cause bloodshed," Mohammed Al Jaber said on Twitter.
The country's Human Rights Minister, Mohamed Askar, called on the UN's special envoy to Yemen, Martin Griffiths, to condemn this act "that is sabotaging the organisation's peace efforts".
"These acts only benefit extremists and will prolong the conflict," Mr Askar said.
On Wednesday a UN official told The National that Mr Griffiths' mandate "does not include monitoring of human rights".
Yemen has been embroiled in a four-year war begun by the Iran-aligned rebels. Tens of thousands of people have been killed and millions left on the brink of famine, the UN says.
Security in Aden has improved in recent months as the Arab Coalition has trained and supported tens of thousands of local police and the UAE has helped establish a counter-terrorism force of six units, each with 100 members.
The Houthis regularly launch ballistic missile and drone attacks on government forces and over the border at targets in Saudi Arabia, but they are not known for suicide attacks.
Previous suicide bombings have been claimed by ISIS or Al Qaeda in the Arabian Peninsula. Despite gains by government forces, both groups remain a threat.
Last February, a suicide attack claimed by ISIS in Aden killed a mother and three of her children outside a military base.
At least 40 others were wounded when the bombers detonated their explosive-rigged vehicles in the Gold Mohur area of Aden's Al Tawahi district.
Officials say those killed included a member of Aden's elite counter-terrorism forces.
Two other attackers wearing explosive belts also tried to climb over the gate of the military base but were shot dead by guards before they could blow themselves up.