* Explosion at army barracks in northern town
* Second, smaller blast outside capital
* Blasts come hours after president sworn in
(Adds hospital spokesman, details of location)
By Abdulwahab Muhammad
BAUCHI, Nigeria, May 29 (Reuters) - A bomb blast rocked a popular drinking spot inside an army barracks in northern Nigeria on Sunday, killing a dozen people hours after President Goodluck Jonathan was sworn in for his first full term.
A rescue worker who asked not to be identified told Reuters his colleagues had counted 12 dead bodies and that around 25 people had been wounded by the blast. A hospital spokesman said 10 corpses had been brought in, four of them women.
The explosion hit the Mamy market in the barracks on the edge of the city of Bauchi at around 8 p.m. (1900 GMT), police commissioner Muhammed Indabawa said. He said it was not clear who was responsible and that no arrests had yet been made.
"It was a very strong and powerful explosion," said Yushua Shuaib, spokesman for the National Emergency Management Agency (NEMA), adding members of the agency were evacuating the wounded. He declined to comment on the death toll.
Military barracks in Nigeria sometimes contain small market areas where traders are allowed to sell food, drink and other goods to both soldiers and members of the public. Mamy market is a popular evening drinking spot for Bauchi residents.
A second, smaller explosion hit a beer parlour in Zuba on the outskirts of the capital Abuja, although the cause was unknown and there were only three minor injuries, Shuaib said.
The blasts underline the challenges Jonathan faces uniting Africa's most populous nation after elections last month which, while deemed the most credible in decades, also exposed the country's religious and ethnic fault lines.
Hundreds of people were killed in northern towns last month in riots and reprisal killings after Jonathan, a Christian from the south, was declared winner of the election, beating northern Muslim and former army ruler Muhammadu Buhari.
"We will not allow anyone to exploit differences in creed or tongue to set us one against another," Jonathan said in a speech at his inauguration ceremony.
Bauchi neighbours Plateau state in Nigeria's "Middle Belt" where the mostly Muslim north meets the predominantly Christian south, a region beset by years of sectarian violence.
The worst of the post-election unrest was in the southern part of Kaduna state, which shares the ethnic and religious diversity of the rest of the Middle Belt, with Christian and Muslim towns and villages set side by side.
Security sources have said they fear radical groups such as Boko Haram, an Islamist sect based in the remote northeast, could increasingly try to strike beyond their home turf.
Boko Haram has carried out frequent fire bombings of police stations and government buildings around the northeastern city of Maiduguri and also claimed responsibility for Christmas Eve bombings in the Middle Belt city of Jos.
Security in Abuja was tight for Jonathan's inauguration earlier on Sunday with joint police and army checkpoints on all roads into the city, bomb squad officers on the streets and helicopters buzzing overhead.
There were several bomb blasts at campaign rallies in the run-up to the April elections, most of them using home-made improvised devices and carried out by unknown assailants.
Militants from the southern Niger Delta oil region claimed car bombs which killed 10 people near a parade in Abuja last October but the movement responsible, MEND, has since been largely inactive.
The perpetrators of a second car bombing in Abuja on New Year's Eve, also at a popular market close to an army barracks, have still not been identified. (Writing by Nick Tattersall; Editing by Mark Trevelyan)