Buenos Aires' two airports reopened Wednesday, after two days of no activity due to a cloud of ash from a Chilean volcano, dpa reported. Montevideo airport also reopened late Tuesday. Elsewhere, operations at Australia's Perth airport had to be closed down almost completely Wednesday as the volcanic ash cloud caused all airlines to ground their planes. However, the ash cloud had drifted west from Adelaide and Melbourne, allowing airports there to restart flights after several days of cancellations. The Volcanic Ash Advisory Centre in Darwin said the ash cloud had split, with a new cloud developing at the lower altitude of 15,000 feet (4,570 metres), making it too dangerous to fly. Forecasters predict the ash cloud will stay over the south western tip of Australia for 24 hours. It is the fourth day of air chaos in Australia due to the ash cloud. The Caulle volcanic cordon is in the southern Chilean Andes, some 800 kilometres south of Santiago and on the Chilean-Argentine border. It erupted on June 4, sending ash and other debris into the atmosphere. It has since disrupted the plans of UN Secretary General Ban Ki-moon, Uruguayan President Jose Mujica, the Argentine national football team and thousands of anonymous travellers. Experts have stressed that the eruption could go on for weeks, or even months, although it weakened in recent days. The ash cloud was moving west at 100 kilometres per hour and was expected to complete a tour round the world by Friday, Chilean experts said. Many airlines regard the presence of ash in the atmosphere as a risk to plane turbines, and opt not to fly in such conditions. The situation has already cost airlines millions of dollars.