overture

s to the al-Ahmar tribal group, President Saleh's most determined opponents.

Jon Leyne

Police in Pakistan say 18 people have been killed in a bomb explosion in a bakery in the town of Nowshera, in the northwest of the country. Details are still coming in.

World News from the BBC

Exit polls in Portugal suggest the centre-right opposition Social Democrats have won the general election. Although they are not expected to have an

overall

majority, the BBC Lisbon correspondent says the Social Democrats will be able to form a stable coalition with their traditional allies, the conservative People's Party. The early election was called after the governing Portuguese Socialists were forced to

request

a big economic bailout from the European Union and the International Monetary Fund.

Voting is taking place in Peru in what's expected to be a closely-fought presidential run-off. Keiko Fujimori, who's the daughter of the former right-wing President Alberto Fujimori, is facing a populist, former army officer Ollanta Humala. Ms Fujimori has campaigned on a programme of free market reforms, but critics fear she may pardon her jailed father if she's elected. Mr Humala, meanwhile, has been accused of being too close to the left-wing Venezuelan President Hugo Chavez, an accusation he denies.

Nuclear scientists say they've made a dramatic breakthrough in the

elusive

quest for anti-matter, a crucial component in the Big Bang theory for the origin of the Universe. Teams using the giant Cern particle accelerator deep under the Swiss-French border say they've succeeded in storing anti-hydrogen atoms. Imogen Foulkes reports from Geneva.