More than 40 people have been killed in a suicide bombing in the centre of Yemen's capital and and car bomb attacks against two military bases in eastern Hadarmout province.
A witness told the Reuters news agency on Thursday that they had counted at least 20 bodies in the suicide attack in Tahrir Square in Sanaa. Dozens more were injured in the blast, including children.
Al Jazeera's correspondent in the capital said the explosion seemed to have been targeting a gathering of Houthis in the square, who were planning to stage a protest.
Our correspondent added that witnesses told him that the attack showed the hallmarks of al-Qaeda, although no one has yet claimed responsibilty.
In eastern Hadarmout province, a car bomb struck an army checkpoint, while 13 soldiers were killed in another car bomb attack on al-Mukalla army base.
The blasts come a day after Ahmed Awad bin Mubarak, picked to be Yemen's prime minister as part of a UN-brokered peace deal, turned down the offer. Houthi rebels had rejected his nomination.
The Houthi rebels swooped south into the capital city from their Sadaa stronghold in the north last month, demanding a new government and more political power for their community.
In addition to the Houthi advance, Yemeni authorities also had to deal with southern secessionist aspirations and a bloody campaign by the al-Qaeda franchise operating in the country.
Impoverished Yemen, which borders oil-rich Saudi Arabia, is a key US ally in the fight against Al-Qaeda, which has carried out persistent attacks on the security forces.
Western and Gulf Arab countries are worried that instability in Yemen could strengthen the armed group and have supported a UN-backed political transition since 2012 led by President Abd-Rabbu Mansour Hadi meant to shepherd the country to stability after decades of autocracy.

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Explaining Yemen's political-military groups:
Houthis - Shia group also known as Ansarullah, or Partisans of God, who have been at war with the government since 2004. They demand resignation of government, more political inclusion and access to the sea. Strongholds include Saada, al-Jawf and the Jeraf district inside Sanaa.
Al-Islah (Reform) - Sunni Islamist party that draws support and membership from heavily armed Sunni tribesmen, and is instrumental in rallying support behind the army and the government. Present in almost all of Yemen. The Houthis have identified the party as its arch-enemy.
Al-Qaeda in the Arabian Peninsula - A merger of the Yemeni and Saudi branches of al-Qaeda. Seized large swathes of territory in the south and the southeast after the uprising in 2011. Launched many attacks on armed forces and central authority establishments. Its power bases are Shabwah, Abyan and Hadramawt.
The Southern Separatist Movement - Umbrella group that wants the south to break away from the north and reinstate the former Socialist state that existed until 1990. Led by Ali al-Beidh.

Scores dead in blasts in Sanaa and east Yemen