Islamabad, Aug 19 (DPA) The UN Thursday doubled to four million its estimate of the number of people left homeless by floods in Pakistan as the deaths of three children in a relief camp intensified fears of disease outbreaks.

UN officials have said that millions of displaced people are living under open skies, apparently without access to clean drinking water and proper food.

‘Our estimates show that over four million people in Sindh and Punjab still do not have a roof over their heads,’ UN spokesman Maurizio Giuliano said of Pakistan’s southern and central regions, which were badly hit by the floods.

Meanwhile, at least three children have died after drinking contaminated water in a relief camp for flood victims in the southern port city of Karachi, an aid worker said Thursday.

The deaths have raised fears among aid agencies that more children could fall prey to water-borne and other flood-related diseases.

‘Three children have died due to gastroenteritis, a disease caused by impure water, in the camp,’ said Qamar Abbas, spokesman for Edhi, a local humanitarian organisation.

The children — one girl and two boys — were aged two-and-a-half to six, Abbas said.

‘These deaths are a matter of great concern for us,’ he said.

Floods have displaced 20 million people in Pakistan and submerged one-fifth of the country as aid workers and officials are struggling to provide aid to the victims.

UN Secretary General Ban Ki-moon planned to meet with the UN General Assembly Thursday to discuss the international response to the floods.

The world assembly last week launched an emergency appeal for $460 million for Pakistan, but the donor community has been slow to respond as transparency in the use of aid is a major issue in Pakistan.