The international disaster-relief community is overstretched, with killer earthquakes, hurricanes and famines from New Orleans to Niger and Pakistan competing for public attention and charitable dollars, according to U.N. and private relief officials.

The amount of donations for the deadly earthquake in Pakistan and flooding in Central America have come in at a slower pace than for other recent calamities, officials say. Two major disasters during the past year -- Hurricane Katrina and the Indian Ocean tsunami -- have sapped funding for other causes and contributed to what experts call "donor fatigue" among governments that finance the United Nations' efforts and individual givers who support private agencies.

"I've never seen a year quite like this one," said Carolyn Miles, the head of operations for the relief agency Save the Children.

The United Nations is struggling to tap new sources of funding, including corporations that contributed more than $700 million to the Indian Ocean tsunami relief effort, and establish a more reliable funding stream through a Global Emergency Fund. It has also stepped up pressure on oil-rich countries in the Persian Gulf area to provide regular contributions to the more than 25 emergency relief operations it has around the world. U.N. relief agencies, meanwhile, have been borrowing helicopters and staff from other relief operations around the world to respond to the Pakistani quake.

"Our resources are extremely strained," said Hansjoerg Strohmeyer, a senior official in the U.N. Office for the Coordination of Humanitarian Affairs. "Our main concern still remains the funding."

Government pledges to victims of the Oct. 8 earthquake in Pakistan have reached more than $150 million, a considerable figure, but only a small fraction of the billions of dollars in pledges made by governments to the tsunami victims. The United Nations, which issued an appeal for $272 million for Pakistan, has received pledges of $50 million.

The varying levels of aid in part reflect the scale of the disasters. The Dec. 26 tsunami killed more than 200,000 people in nine countries, while the Pakistani earthquake has killed more than 25,000 people along the India-Pakistan border and driven more than 2.5 million from their homes.

But the rare occurrence of such a deadly tidal wave and the impact it had on travel destinations catering to western tourists generated unprecedented attention and giving. "We saw tourists fleeing for their lives," said Trevor Rowe, a spokesman for the World Food Program. "We don't have that in Pakistan."

Rowe said that U.N. agencies have faced a growing number of natural disasters over the past 15 years. He cited a study by the German insurance company Munich Re that documents a nearly threefold increase in natural disasters from the 1960s to the 1990s.

Save the Children maintains that overall funding to relief agencies has dropped since the tsunami. The organization raised more than $5 million in donations in the first week after the tsunami struck. So far, it has taken in nearly $1 million for earthquake victims in Pakistan and India and $8,000 for Central American flood victims. "We saw a tremendous outpouring of support for the tsunami and less support for emergencies that followed," said Eileen Burke of Save the Children.

U.N. officials and private relief agencies say that, while governments and the public continue to fund far-away operations, they have had trouble focusing attention on more than one disaster at a time.

Private contributors gave more than $40,000 this August in response to a Care USA Internet appeal for Niger famine victims. But the donations dried up immediately after Hurricane Katrina hit the Gulf Coast, driving hundreds of thousands from their homes and inundating large sections of New Orleans. "In August, we were getting a surprisingly large number [of donations] for Niger after the BBC and CNN started flashing pictures of children starving, but Katrina knocked Niger off the map," said Lurma Rackley, the head of public relations for Care USA.

The American Red Cross raised $1.2 billion for Katrina and $556 million for the tsunami. But it has so far raised $1.6 million for Pakistan and does not keep figures on the Central American floods.

Pakistan's case for funding has received a boost from the Bush administration, which pledged an initial $50 million and donated helicopters and other military equipment to participate in the relief effort. The United States hopes that its expression of generosity will also bolster its standing in the Muslim state. "Pakistan's a friend, and America will help," Bush said Friday. "And so not only will we offer our prayers, but we'll offer our help, to help the people, to help the government, to help this great nation get back on its feet."

U.N. officials and relief agencies say that the initial response to Pakistan has been far more promising than for Central America, where at least 2,000 people died from flooding and mudslides. The United Nations has received $3 million of the $30 million it requested for Guatemala and El Salvador. Most of that, about $2.5 million, came from Sweden. The Bush administration has also pledged about $1.9 million in aid to Guatemala and El Salvador.

"The disparities with Central America are stark," said George Rupp, president of the International Rescue Committee. Rupp said that Katrina has made Americans much more sensitive to the needs of foreigners afflicted by natural calamities. But he said it has also made them more mindful of the limits of aid in getting people back on their feet. "They have a more sober understanding of the limits to what a contribution can achieve," he said. "I guess we could say that's a form of donor fatigue."