The death toll from Typhoon Haiyan has now reached 4,000, according to a notice at Tacloban city hall.

The figure is the first public acknowledgement that the number of fatalities has exceeded an estimate provided by Philippine President Benigno Aquino, who said this week the predicted death toll would be closer to 2,500.

On Thursday, official confirmed deaths nationwide stood at 2,357 after the November 8 typhoon - one of the strongest ever recorded.

President Aquino has faced mounting pressure to speed up the distribution of aid.

There has also been confusion over the number of fatalities in the disaster.

A notice board in Tacloban City Hall said the toll had doubled overnight to 4,000 deaths.

The notice first said the figure was for Tacloban alone, before mayor Alfred Romualdez apologised and said it was for the whole central Philippines.

The figure is compiled by local officials who began burying bodies in a mass grave on Thursday.

The UN has put the latest overall death toll at 4,460 but an official said it was now reviewing the figure.

Preliminary numbers of those missing remained at 22,000, according to the Red Cross.

Tacloban Mayor Alfred Romualdez said some victims may have been swept out to sea after a tsunami-like wall of seawater slammed into coastal areas.

Aquino said initial estimates of 10,000 dead by local officials were overstated by "emotional trauma".

Survivors have grown increasingly desperate and angry over the speed of aid distribution, which has been hindered by looting, a lack of fuel for rescue vehicles and debris-choked roads.

It comes as helicopters from the USS George Washington aircraft carrier began flying food, water and medical teams to ravaged regions on the islands.