River defences in Pakistan's flood-hit south were bolstered Tuesday in a bid to save two towns from catastrophic flooding as the UN warned the world community must help the militant-hit nation recover. Eight million people remain reliant on aid handouts to survive, six weeks after monsoons caused devastating floods in the country's worst disaster in living memory. Advancing floodwaters continue to threaten the towns of Johi and Dadu in Sindh province, with 19 of its 23 districts deluged and 2.8 million people displaced, according to provincial authorities. Armed forces and irrigation officials are racing against time to save Johi and Dadu, said provincial irrigation minister Jam Saifullah Dharejo.