His office, which has an annual budget of $250 million, was continuously asked to monitor crises, investigate abuses and undertake the training of officials and security forces to prevent human rights violations. Doing that with the resources provided by member states and facing a $25 million shortfall in funding this year was “like being asked to use a bucket and a boat to cope with a flood,” Mr. Zeid said.

His comments echoed aid agencies’ increasingly strident calls for greater action by world powers to prevent crises that are similarly exhausting their financial and human resources.

Commissions documenting atrocities in Syria and North Korea are among six inquiry panels supported by the United Nations human rights office, more than ever, together with teams monitoring developments and documenting abuses in a number of crises, including Iraq and Ukraine. The office also had several requests to open or retain field offices and dozens of requests to deploy human rights advisers, which it feared it would be unable to fulfill, Mr. Zeid said.

Mr. Zeid said it was “particularly painful” that one of the first things he would have to do as the human rights chief was cut staff and programs. There is, he said, an “extraordinary disconnect between what we are asked to do and what we are given to do it with.”

Although human rights ranks, along with security and development, as one of the three pillars of the United Nations, it receives just 3 percent of the budget, and this covered about one-third of its activities, Mr. Zeid said. The rest of its funding came from voluntary contributions, but these had not kept pace with the demands for action from governments. “The office is stretched to the limit,” he said. “We are already paring back everything we can, and services are starting to suffer.”

As a point of comparison, he said, residents of Switzerland spent 10 times as much on chocolate last year as the annual amount the human rights office would receive from the United Nations budget this year and in 2015, he said.

"We are not asking for very much,” Mr. Zeid said, contrasting his office’s modest budget with the United Nations’ $1.3 billion for security and $1.1 billion for development. He pointed out that a number of governments had proposed that the share of the budget should increase to 5 percent.