The United Nations has begun a large-scale aid distribution in Haiti's capital aiming to feed two million people nearly three weeks after the deadly earthquake. Only women will be able to collect the aid from 16 centres exchanging vouchers for sacks of rice to give to their children and families. Each woman will receive a 25kg bag of rice enough to feed her family for two weeks.The aid effort comes as 10 Americans were detained by Haitian authorities. They are suspected of trying to take more than 30 children out the country without proper authorisation. Haitian Social Affairs Minister Yves Christallin said police had arrested five men and five women travelling with 33 children on the border with the Dominican Republic.The UN estimates that up to a third of the population will be reliant on some kind of relief in the months to come.