U.N. sanctions punishing North Korea for its reported nuclear test should not target crucial aid deliveries keeping millions of North Korean civilians alive, the United Nations' top humanitarian official said Wednesday.

"It is not the leaders who will starve and freeze this winter -- it is the most vulnerable," Jan Egeland, the U.N. undersecretary-general for humanitarian affairs, told reporters in Geneva.

He said the U.N. and Red Cross shipments of food and medicine to the isolated communist nation are "of vital, lifesaving importance" for North Korean civilians and urged that humanitarian efforts be spared in any sanctions.

"The food should continue and it should be funded by generous donors," Egeland said at the global body's European headquarters.

CountryWatch: North Korea

Pyongyang shocked the world Monday by claiming to have conducted an underground nuclear bomb test, prompting worldwide condemnation and triggering an international campaign for U.N. Security Council sanctions.

Council members are still debating how severe to set the sanctions against North Korea. China said its communist ally should face "some punitive actions" while the U.S. and others are pushing for tougher sanctions, including a ban on imports of military goods and luxury items, and a crackdown on illegal financial dealings.

Last year, Egeland's office was asked to leave North Korea when the regime said it wanted all emergency humanitarian assistance from international organizations to stop by the end of the year, partly because of what it called political interference from the United States.

Click here to go to FOXNews.com's United Nations Center.

Egeland said it was fortunate that some food assistance could continue. The nation of 22 million people has relied on foreign assistance since natural disasters and mismanagement caused its economy to collapse in the mid-1990s.

Experts says as many as 2 million North Koreans may have died of hunger during the 1990s.

The U.N. food agency said last month that it would run out of food supplies for North Korea within two months due to a lack of donations for its operations there. It had previously fed 6 million people annually in the North, but scaled back its program after Pyongyang's action against aid groups last year.

Click here to go to FOXNews.com's North Korea Center.