US Republican candidate Donald Trump has arrived in Mexico to meet President Enrique Pena Nieto. The trip is contentious as during his campaign Mr Trump has branded Mexican migrants "rapists" and "murderers", and vowed to build a wall along the border. He will face protests on his visit, with ex-President Vicente Fox among those saying he is not welcome. Mr Trump will later fly to Phoenix, Arizona, to deliver a key speech on measures to tackle illegal immigration.