Global military spending continued to climb last year as energy prices rose, and an increased number of peacekeeping missions threatened to overextend the United Nations and other international organizations, a Swedish peace institute said Monday.

The world spent a total of US$1.12 trillion (euro8.9 billion) on military expenditures during 2005, an increase of 3.4 percent from 2004, when adjusted for inflation and changes in exchange rates, according to a report by the Stockholm International Peace Research Institute.

The figure corresponds to 2.5 percent of the global gross domestic product, which is a decrease from 2.6 percent the year before.

The United States accounted for 48 percent of all military spending, an increase by 1 percent from last year as costly campaigns in Iraq and Afghanistan continued and Hurricane Katrina forced emergency operations at home, the institute said.

The group, established 40 years ago and largely funded by the Swedish government, is a world leader in tracking the arms trade and analyzing military spending.

The report's "facts tell you the unfortunate truth that the great masses of money spent ... are not for peace missions," the organization's director Alyson J.K. Baites said.

The institute attributed the global increase last year in part to higher oil and mineral revenues, which "boosted government revenues and freed up funds for military spending" in countries like Russia, Saudi Arabia and Algeria.

"With rising revenues from natural resources such as gas oil and metals, these countries diverted those funds into military spending, particularly into arms purchases," institute researcher Petter Stalenheim said. "That is why the Middle East, together with North America, was the region with the greatest increase in military expenditure."

Major armed conflicts continued to shift from wars between nations to battling non-state groups such as terrorists and insurgency groups, the report said.

"Dealing with the activity of non-state actors is at the heart of the challenges faced by the international community in responding to conflict," the report said.

In a chapter devoted to Iraq, the report said that "persistent wrangling over the nature of political representation, combined with the extreme levels of violence ... continued to hamper any real movement toward peace."

"What most clearly stands out from Iraq is our failure to understand the motivation and composition of the insurgency and therefore the ability to identify entry points for dialogue," Iraq analyst Caroline Holmqvist told The Associated Press.

The U.S.-led force in Iraq was confronted last year with a paradoxical situation — its presence in the country continued to provide incentive for a "very fluid and decentralized insurgency," while departure amid the highly insecure conditions would be regarded as abdication of responsibility, the report said.

The report also warned that the growing number of peacekeeping missions around the world may be too many for the U.N. and other organizations to handle.

While a total of 40 multilateral peacekeeping missions were launched between 1948 and 1989, there were 58 such missions ongoing in the world during 2005, the report said.

"The sheer number of missions and their increasingly complex nature are arguably putting the U.N. and other organizations in danger of over-stretching institutional capacities," it said.

The European Union launched six new civilian peacekeeping missions during the year, which SIPRI said "is testimony to the EU's deepening commitment to be a global security actor."

Analyzing nuclear arms control and nonproliferation efforts, the report warned that "even though Iran has been almost exclusively the focus of talks on nuclear weapons, democratic accountability regarding nuclear weapons should not be a concern only in the transitional or authoritarian states, but also in consolidated democracies."

There remain large uncertainties about global inventories of nuclear weapons and weapons-usable fissile materials, he said.