The pilot was above his desired descent profile so he selected the landing gear down before entering the circuit area. On arrival in the circuit area, the radio became inoperative due to an electrical failure and the pilot was given a green light by the tower controller as a clearance to land. Shortly after the nosewheel contacted the runway, it collapsed, followed almost immediately by the right main landing gear collapsing. The aircraft slewed right and came to rest off the sealed surface approximately 250 metres from the departure end of the runway. The pilot indicated that, althought it was his habit to check the green landing gear light and the mechanical indicator after selecting the landing gear down and prior to landing, he could not recall whether he had done so on this occasion.