A cholera outbreak is rapidly spreading across Syria, threatening the lives of millions of people, the United Nations said Tuesday, as it sought to raise $34.4 million for a three-month response plan.

The money is needed to assist more than 160,000 people with health services and 5 million with water, sanitation and hygiene assistance.

"More than 24,000 suspected cholera cases have been reported and cases have been confirmed now in all 14 governorates. At least 80 people have died so far," U.N. humanitarian official Reena Ghelani told the U.N. Security Council.

She said millions across the war-torn country face severe water shortages in Hassakeh, al-Bab and Aleppo.

"The crisis is likely to get even worse: The outlook from now to December suggests an increased probability for below-normal precipitation and above-normal temperatures. If this materializes, it will further exacerbate an already dire water crisis," she said.

Some 2 million people depend on humanitarian assistance to meet basic needs as winter approaches in the opposition-held northwest. Most are women and children living in camps with limited or no access to heating, electricity, water or sewage disposal.

"We are just weeks away from another winter in Syria and a painfully familiar scenario will soon unfold again," said Ghelani.

She urged continued cross-border access and increased cross-line access to provide humanitarian aid to Syrians in dire need.

"A non-renewal of the authorization to carry out cross-border humanitarian assistance at the peak of winter, and in the middle of a cholera response, could cut off access to millions of people in northwest Syria when they need it most,'' she warned.

Confidence-building measures needed for cooperation

U.N. Special Envoy for Syria Geir Pedersen also briefed the Security Council and said the political process has not yet been delivered for the Syrian people and they continue to suffer.

"The key Syrian and international stakeholders need to rebuild their confidence that cooperation on Syria is possible, that the other side is willing and able to deliver, and that Syria can be firewalled from other conflicts,'' he said. ''That confidence can only be built by concrete actions. To serve that purpose, initial steps must be precise, reciprocal, verifiable and implemented in parallel – and address daily concerns of the Syrian people.''

Syria has been locked in a vicious civil war since early 2011 when the Assad regime cracked down on pro-democracy protests.

Hundreds of thousands of people have been killed and more than 10 million have been displaced, according to the U.N.