Tens of thousands of tsunami survivors are at risk from killer diseases, such as cholera, despite stepped up international aid, the World Health Organisation (WHO) said on Saturday. WHO crisis chief David Nabarro, asked whether an earlier warning that some 50,000 people could succumb to disease still stood, said: "It is still too early to make that judgement." Nearly 130,000 people are known to have died when a massive earthquake off Indonesia's Sumatra island on Sunday sent walls of water crashing onto shorelines as far away as Somalia. But with five million people short of either water, food or basic sanitation across the Indian Ocean, a further toll of 50,000 from disease and other causes would be in line with that seen in earlier humanitarian emergencies, Nabarro said. "At the moment the international operation is incredibly strong...in getting relief to airports. But we still have to be sure we have got the necessary relief reaching people," he said. There were reports of diarrhoea, which can be particularly dangerous to children, amongst those left homeless in India and Sri Lanka, while the situation in Indonesia's Aceh province was still unclear. --More 2107 Local Time 1807 GMT