At least 43 people were killed when a powerful bomb ripped through the Yemeni capital, plunging the violence-plagued state into further turmoil after weeks of political deadlock.
Dozens more were wounded in the suicide attack on Thursday in Sanaa's Al-Tahrir square, which targeted a gathering for supporters of Shi'ite insurgents who overran the capital last month.
A separate suicide attack killed 20 Yemeni soldiers in the country's southeast in a car bombing suspected of having been carried out by al-Qaeda, a military source said.
Yemen has been racked by political turmoil and sporadic violence since the 2012 toppling of strongman Ali Abdullah Saleh, with rebels and militants battling to exploit a power vacuum and seize control of territory.
The bombing in Sanaa came a day after Yemen's new prime minister designate, named as part of a UN-brokered peace deal, refused the post amid fierce rebel opposition.
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Witnesses said a suicide bomber detonated an explosive belt at a checkpoint at the entrance to the protest gathering, adding that steel balls were seen strewn at the scene of the blast.
A photographer saw the lifeless bodies of four children among the victims.
Medics at the nearby Police Hospital issued an urgent plea for more doctors to deal with the number of casualties.
Supporters of the rebels, known as Huthis, gathered after the blast - the largest in Sanaa since May 2012 - demanding the fall of beleaguered President Abdrabuh Mansur Hadi.
The Huthis, who are also referred to as Ansarullah, swept into the capital on September 21 after fierce battles with forces allied to the government in Sanaa that left more than 270 dead.
A UN-brokered peace accord, which called for a rebel withdrawal from Sanaa and the naming of a neutral premier, was struck the same day.
But the Huthis have dug their heels in, refusing to support Hadi's choice for prime minister and demanding a greater role in decision making as well as political and economic reform.
In addition to the Huthis swooping south from their Saada stronghold in the north, the authorities have also had to deal with southern secessionist aspirations and a bloody campaign by the country's al-Qaeda franchise.
The 20 Yemeni soldiers were killed on Thursday when a suspected al-Qaeda operative detonated his explosives-laden car at an army post on the western outskirts of the southern city of Mukalla, a military official said.
A tank and two army vehicles were destroyed in the blast, the official added.
On Wednesday, suspected al-Qaeda militants launched a wave of dawn attacks on police and the army in another central town, killing 10 policemen.
Yemen remains in political deadlock after Hadi infuriated the rebels in Sanaa earlier this week by naming his chief of staff, Ahmed Awad bin Mubarak, as prime minister as part of the UN's reconciliation accord.
In a statement on Wednesday the rebels said bin Mubarak's appointment had been "against the will of the nation" and "at the behest of outside forces," an apparent reference to US and Saudi influence.
Rebel leader Abdulmalik al-Huthi had reportedly called late Wednesday for protests in Sanaa against the appointment.
