The United Nations aid agencies have said the humanitarian situation in Bangladesh after November's devastating cyclone is much worse than previously understood and appealed to the international community to provide more funds for their relief operations.

The agencies have upped the estimated number of people affected to more than 8.5 million, 1.5 million more than they had reported earlier.

As more information becomes available, an even grimmer reality is being revealed, they said, noting that about 2.6 million Bangladeshis across nine districts of the South Asian delta country still need immediate life-saving assistance.

The death toll has increased slightly to 3,268, the number of people considered missing is 872 and the number of injured has been revised upward by 5,000 to almost 40,000.

The material damage is also more severe than earlier reported. Nearly 564,000 homes have been completely destroyed, a leap of 200,000 on earlier reports, while another 885,280 houses have been damaged.

The agencies say at least 1.25 million livestock have been confirmed killed, more than twice the previous estimate, and the area of cropland damaged has risen to 2 million acres.

Food, shelter and cash remain the three highest priority areas for emergency assistance, according to the latest UN humanitarian assessments, but sanitation, drinking water, electricity and livelihood assistance are also seen as critical.

So far the UN Central Emergency Response Fund has disbursed $14.7 million to help with relief efforts in the most affected areas of Bangladesh, while international donors have contributed over $143 million.