A suicide bombing claimed by al Qaeda killed at least 26 people outside a presidential palace in southern Yemen on Saturday, hours after the newly-elected president was sworn in and said the battle against the Islamists was a "national duty".
A car was driven at the gates of the building in the port city of Mukalla, Yemen's fourth-largest city, far from the capital Sanaa where Abd-Rabbu Mansour Hadi was sworn in.
Dozens were injured. The governor of Hadramout province Khalid Saeed al-Dayni said 20 of the dead were soldiers and an investigation was under way to identify the suicide bomber.
Al Qaeda claimed responsibility and said the attack had been carried out by a "Yemeni jihadi", according to text messages sent to Reuters and other media outlets.
"The sound of the explosion was strong and was heard in many parts of the city," a resident of Mukalla said.
"The strength of the explosion shattered glass windowpanes and doors in buildings near the explosion."
Sanaa, the scene of much fighting in recent months between factions of the army supporting protesters and units loyal to the former leader, was relatively quiet.
After taking the oath, Hadi singled out al Qaeda, whose active Arabian Peninsula branch is based in Yemen, as a top priority for his new administration, saying: "Continuing the war against al Qaeda is a national and religious duty."
The former army general was the sole election candidate to replace Ali Abdullah Saleh, who ruled Yemen for three decades with an iron fist but was pushed out by months of street protests sparked by the Arab Spring.
While the protests and bouts of bloody repression by security forces have subsided, Yemen remains mired in mass poverty, unemployment and corruption, rocked by rebellions in the north and south, and threatened by al Qaeda.
Saudi Arabia and the United States long saw Saleh as the main bulwark against al Qaeda in Yemen, which sits on one of the world's main oil shipping routes, but threw their weight behind a power transfer deal as protests against him grew.
Some 42 percent of Yemen's population of 23 million live on less than $2 per day, fuel and water shortages are chronic and inflation is rampant.
Hadi said in a speech that Yemen must draw a line under a year of protests and violence and turn its attention to economic problems and the job of returning those displaced by the crisis to their homes.
"I stand here at a historic moment ... I look to the Yemeni people and give them thanks. The crisis reached every city and village and house, but Yemen will continue to go forward," Hadi said.
"If we don't deal with challenges practically, then chaos will reign."
Jamal Benomar, UN envoy to Yemen, said: "Yemenis want an end to the crisis, and to turn a new page. Now it's time to rebuild, for consensus and concord ... and to bring people into an inclusive political process."
The U.S. ambassador to Yemen, Gerald Feierstein, said: "We are seeing the beginning of a process that I believe will deliver great results over the next two years."
Hadi now has the job of overseeing a two-year political transition that foresees parliamentary elections, a new constitution and a restructuring of the military, in which Saleh's son and nephew still hold power.
An inauguration ceremony is scheduled for Monday. Saleh, who returned to Yemen early on Saturday after seeking treatment in the United States for injuries suffered in an assassination attempt last year, is due to attend.
After the speech, protesters in the southern city of Aden clashed with security forces, killing a soldier, a local security official said. Two soldiers and two protesters were injured, medics added.