Kate Middleton and Prince William visit UNICEF center in Denmark

Prince William and his wife, Kate Middleton, on Wednesday helped pack dozens of U.N. emergency supplies in Denmark to be distributed in East Africa, where a food shortage is affecting an estimated 13 million people.

The British royal couple visited a UNICEF warehouse in Copenhagen to draw attention to the crisis, which Middleton called "shocking." They were assisted by Denmark's Crown Prince Frederik and Australian-born Crown Princess Mary, who were married in 2004.

The United Nations says hundreds of thousands of Somalis, many fleeing fighting and drought in their home country, are especially at risk of starvation.

Prince William appealed for help and said the crisis had been going on for "at least 100 days now, and it's not getting any better."

"The rains have come now and ... that doesn't necessarily mean things are going to get better at all. In fact, disease becomes a huge issue," William said. "And so it's very much a case of anyone who can do anything to help, please do."

The royals were each assigned a packer inside the U.N. warehouse where they stacked medicine and basic emergency medical supplies in cardboard boxes on conveyor belts. Later in the day, the cargo was to be flown to the Kenyan capital, Nairobi.

Before helping in the packing, William and his wife were treated to lunch at the Amalienborg Palace, home of the Danish royals. They were also briefed on nutrition and watched a video on the East Africa situation.

"It's really just how shocking the situation still is," said Middleton, who bears the title Duchess of Cambridge. "A huge amount still has to happen with hundreds of children still malnourished at the moment."

The UNICEF supply division in the Danish capital coordinates the distribution of emergency food and medical supplies worldwide, including nutritional treatments for some 320,000 severely malnourished children in East Africa.

Established in 1962, the 270,000-square-foot (25,000-square-meter) storehouse has its own loading port. Supplies include 30 different prepackaged kits, which are usually transported by ship, although aircraft are used in emergencies including volcanoes, earthquakes, civil unrest, tsunamis and wars.

The visit to Denmark is the British royal couple's first overseas trip since a lengthy sojourn to Canada and the United States during the summer.

Africa has been of special interest to William, who has traveled there many times. He proposed to Middletonwhile on vacation in Kenya in 2010.