Authorities in Pakistan are still struggling to reach those worst affected by floods, weeks after devastating monsoon rains in the south.
Aid workers, who are also affected by flooding, have had difficulty getting help to the thousands stranded on higher ground, officials told the BBC
Officials say 8 million people have now been affected by the crisis. Last week they put the figure at about 6 million.
This year’s floods in Sindh are thought to be worse than last year’s deluge.
Caused by heavy monsoon rains, the floods have already killed 248 people and damaged or destroyed some 665,000 homes across the province since they began last month.
Officials have also expressed fears about the rapid spread of disease and say that the problems affecting the southern province are only getting more acute.
Already, more than two million people are estimated to be suffering from flood-related diseases following the torrential rain, cases of malaria and diarrhoea are increasing, and at least 7,000 people are being treated for snake bites.
A basic shortage of manpower was the reason cited by officials for the problems in channelling aid to those most in need.
“People who have in the past worked as aid delivery workers are themselves in problems, their homes are inundated and families displaced,” Irshad Bhatti, a spokesman for the National Disaster Management Authority (NDMA), told BBC Urdu.
Mr Bhatti added that a lack of co-ordination between different agencies, officials and the military made matters worse.
“Aid delivery is being carried on by a number of aid agencies and the military, but there is no co-ordination, and as a result efforts of all these entities are proving ineffective,” he said.
The logistical challenge is immense. Large areas are under water, officials say, and thousands of groups of people are taking shelter on patches of high ground in small groups.
Mr Bhatti says that officials have informed the government in Sindh province of the problem and highlighted the urgency of co-ordinating emergency relief.
Last week the United Nations launched an appeal for $365m (£231m) to help those in Sindh and neighbouring Balochistan province affected by the crisis.
The government response to the flooding has been heavily criticised. Correspondents say that the perception is that for a second year running, the government has failed hundreds of thousands of flood victims.
About 23 of Sindh’s 26 districts have been affected by floods.