The United Nations is asking for $164 million US to help fight a deadly cholera outbreak that is spreading throughout Haiti.

A woman carries a child with symptoms of cholera at the entrance of the St. Catherine hospital in the Cité Soleil neigborhood in Port-au-Prince, Haiti, on Thursday. (Ramon Espinosa/Associated Press)

The outbreak of the severe diarrheal disease was first detected in the Artibonite region in late October.

It has since spread to other areas, including the densely populated capital, Port-au-Prince, where more than one million people still live in tents and temporary shelters following January's devastating earthquake.

At least 724 people have died and more than 11,000 people have been admitted to hospital since the outbreak began, the Pan American Health Organization said in a statement Thursday.

Doctors Without Borders (MSF), an emergency medical relief organization, said the outbreak has "taken grip" in Port-au-Prince.

"It’s a really worrying situation for us at the moment," said Stefano Zannini, the head of mission for MSF in Haiti. He said hospitals are overflowing with patients as the number of cases soars.

"In the slum of Cité Soleil, located in the north of the city, yesterday we recorded 216 separate cases of cholera arriving at the hospital, while the total number recorded just five days ago was 30."

He said patients are coming from areas across the city, from slums to wealthier communities.

"At the moment we have 400 beds set aside for the stabilization and rehabilitation of patients and we’re hoping to get that up to 1,000 by the end of the week," he said.

The government is working with relief organizations to increase the number of beds available to cholera patients by setting up 10 new cholera treatment centres to treat people with severe cases.

Funds will be used by the UN and non-governmental organizations to bring in additional doctors, medicine and water-purification equipment to treat up to 200,000 people who could show cholera symptoms ranging from mild diarrhea to severe dehydration, the global body said.

"We absolutely need this money as soon as possible," said Elisabeth Byrs, a spokeswoman for the UN humanitarian office.

She told reporters in Geneva that the funds need to be provided quickly "otherwise all our efforts can be outrun by the epidemic."

The cause of the outbreak in Haiti is still unknown. The country hadn't seen cholera cases for decades before last month.

With files from The Associated Press