The death toll from severe flooding in Myanmar has risen to 69, with 259,799 people affected by the disaster, the ministry of social welfare said on Wednesday.The flooding has submerged vast areas, and four states and regions -- Rakhine, Chin, Sagaing and Magway -- have been declared "natural disaster affected areas", reports Xinhua news agency.Flooding has begun to move southwards and was likely to expand and affect more areas, the meteorology and hydrology department warned.The floods, caused by heavy rainfall since June, has destroyed houses, farmland, railway lines, bridges and roads.