Kenya election: Voting begins in re-run amid tightened security

<p><br></p><p>Voting is under way in Kenya amid tight security in a re-run of the presidential election, which is being boycotted by the main opposition.</p><p>Police have clashed with opposition supporters, some of whom have been blocking access to polling stations.</p><p>President Uhuru Kenyatta was declared the winner in an August vote, but it is being held again over "irregularities".</p>