The United Nations warned Tuesday that Haiti was seeing a sharp increase in cholera infections, with the crisis-wracked country's number of suspected cases almost doubling over just a few days.

"Up until a few days ago, the increase of cases had been gradual but now we are seeing a worryingly sharp increase, so the situation has become more challenging," wrote the UN's humanitarian coordinator in Haiti, Ulrika Richardson, in a blog post published Tuesday.

"Although cholera can be deadly, it is preventable and treatable," she said, adding that "speed is of the essence" to contain the outbreak.

Richardson lauded the "immediate and decisive" UN-supported work by Haitian authorities and NGOs, who continue to face critical shortages of clean water and fuel due to gang blockades.

Between October 20 and 23, the number of suspected cases recorded by Haiti's grew from around 1,000 to nearly 2,000, said the UN secretary-general's spokesperson, Stephane Dujarric.

He added that according to UNICEF, children under the age of 14 made up about half of the cases.

Richardson said she had visited several cholera treatment centers in the most affected neighborhoods of Haiti's capital, where she saw heartbreaking scenes, including "children who were so malnourished, it was difficult to insert a drip into their arms or legs."

Cholera returned to Haiti in early October, three years after the country finally stamped out an outbreak that began in 2010 and killed more than 10,000 people.

Haiti's government has called on the for help with its worsening health and security crises.

The UN Security Council, at the request of Secretary-General Antonio Guterres, is considering sending an international force to restore order.