BBC News with Zoe Diamond

The electoral authorities in Mexico have announced they will recount the votes in more than half the ballot boxes in Sunday's presidential poll after finding

inconsistencies

in the vote tallies. The leader of the left-wing PDR party, Andres Manuel Lopez Obrador, has demanded a total recount after preliminary results put him in second place. The leading candidate, Enrique Pena Nieto, has denied allegations that his party bought votes. From Mexico City, here's Will Grant.

Since the election, numerous videos have emerged on YouTube of people claiming they received credit with a major supermarket chain in exchange for their votes. Mr Pena Nieto dismissed such accusations against him as politically motivated and suggested the videos had been faked by his opponents. 'These things happen in all elections, it's nothing new.' He said of the videos, pointing a finger of blame at his closest challenger, Andres Manuel Lopez Obrador. Mr Lopez Obrador has called for a complete recount of the votes, saying the elections were 'unequal and dirty'.

Scientists around the world have

hailed

the discovery of a particle which could illuminate our understanding of the universe. The team from the Cern Laboratory in Switzerland say their find is consistent with the Higgs boson, which is thought to give atoms their mass and

bind

the universe together. The Nobel Prize-winning physicist Stephen Hawking, who speaks with the aid of a computer, said the discovery was one of the most important of the 21st century.