GENEVA — The United Nations appealed Monday for $16.4 billion to pay for global humanitarian needs in 2015, saying the number of people affected by conflicts and natural disasters around the world has reached record levels.

More than 40 percent of the appeal — $7.2 billion — would go to help 18.2 million people suffering from the war in Syria.

The appeal also covers Central African Republic, Iraq, and South Sudan, the top humanitarian priorities, as well as Afghanistan, Congo, Myanmar, occupied Palestinian territories, Somalia, Ukraine and Yemen.

A year ago, the U.N. asked for $12.9 billion to assist 52 million people, but during 2014, the number of people in need has nearly doubled to a record 102 million, U.N. humanitarian chief Valerie Amos said.

As a result, the U.N. raised its appeal to $17.9 billion for 31 countries, but donors only provided $9.4 billion, Amos said.

That has left $8.5 billion in unmet needs, many of which have been rolled over into the 2015 appeal to help 57.5 million of the world's most vulnerable people.

The 2015 request, on behalf of 455 aid organizations, does not include money to help feed millions facing hunger in Africa's Sahel region, which has seen repeated droughts and conflicts. That appeal is being launched in February.

Amos said aid in 2014 helped avert a famine in South Sudan, fed millions of Syrians each month, provided medical supplies to 1 million Iraqis and paid for food for 903,000 people in Central African Republic.

But with 80 percent of the needy living in conflict-ridden countries, the demands for aid are outstripping the ability to pay for them, Amos said.

She told reporters in Geneva that donors are being asked for more and more funds, "but as needs rise, the resource gap is widening."