The former Chilean dictator Augusto Pinochet has celebrated his 90th birthday against the backdrop of new corruption and human rights charges. He spent the day under house arrest at his home in Santiago surrounded by his family while his lawyers prepared for what analysts say may be his toughest legal battle yet.On Wednesday Pinochet was charged with tax fraud, forging documents and other crimes in a case involving an estimated 23 million euros in hidden foreign bank accounts. A day later he was charged in connection with the disappearance of seven people during his dictatorship between 1973 and 1990. Two previous human rights cases were thrown out by the courts on the grounds that the ailing general was suffering from mild dementia. Recently two judges ruled he was fit to face prosecution.