The United Nations will seek 800 million dollars (£716 million) more in aid from the international community to respond to soaring needs of Pakistani flood survivors, an official has said.

The unprecedented deluges — likely to have been worsened by climate change — have killed 1,678 people in Pakistan since mid-June.

About half a million survivors are still living in tents and makeshift shelters.

Julien Harneis, the UN resident co-ordinator in Pakistan, told reporters in the Pakistani capital Islamabad that the latest appeal will be issued from Geneva on Tuesday.

It comes just weeks after the agency sought 160 million dollars in emergency funding for 33 million people affected by floods.

Mr Harneis said the UN decided to issue the revised appeal “to respond to the extraordinary scale of the devastations” caused by the floods.

Pakistan’s displaced are now facing waterborne and other diseases, he said.

Health officials say the outbreaks have caused more than 300 deaths so far.

Since July, several countries and UN agencies have sent more than 130 flights carrying aid for the victims, many of whom complain they have received too little help or are still waiting for aid.

Officials and experts have blamed the rains and resulting floodwaters on climate change.

UN secretary-general Antonio Guterres visited some of the flood-hit areas earlier this month. He has repeatedly called on the international community to send massive amounts of aid to Pakistan.

The Pakistani government estimates the losses from the floods to be about 30 billion dollars (£26 billion).