KOBE, Japan - Under pressure to make progress toward a new global-warming pact, Group of Eight environment ministers yesterday endorsed cutting greenhouse-gas emissions in half by midcentury, but failed to agree on much more contentious near-term targets.

The three-day meeting in Kobe was dominated by calls from the United Nations, European countries and developing nations to move forward on setting targets for cutting emissions by 2020. Scientists say those targets are needed to avoid the worst effects of global warming.

But the ministers from the United States, Japan, Germany, France, Britain, Canada, Italy and Russia, in a carefully worded statement, mentioned only the need to set such targets eventually. That frustrated environmentalists and some European ministers.

"From a scientific point of view, we need a clear reduction target, because the next 20 years are very vital, very important for climate change and the decisions we make in this process," said Matthias Machnig, Germany's state minister for environment.

The Kobe meeting was meant to set the stage for July's G8 summit in Toyako, Japan.

Japan has put climate change at the center of the agenda, and many are hoping for a strong signal from the summit to bolster wider international talks on global warming.

In their statement, the ministers said there was "strong political will" to reach agreement at the summit to cut emissions 50 percent by 2050. The statement also cited the need for global gas emissions to peak within the next 10 to 20 years, and it called on developing countries with rapidly expanding greenhouse-gas emissions to work to curb the rate of increase.

"As we head toward the Toyako summit, I believe this meeting has provided momentum," Japanese Environment Minister Ichiro Kamoshita said.

The ministers also acknowledged developing nations' demands for help in becoming more energy-efficient, developing their economies more cleanly, and adapting to changes wrought by warming, such as rising sea levels.

The United Nations launched negotiations late last year on a new climate-change pact to take effect when the first phase of the Kyoto Protocol expires at the end of 2012. Negotiators face a deadline of December 2009, when representatives of about 190 nations will meet in Denmark.

Deep divisions, however, have plagued the talks.

European nations support a U.N. scientific finding that emissions cuts of 25 percent to 40 percent by 2020 are needed to stop global temperatures from rising so high they trigger widespread environmental damage.

The United States, however, considers such cuts beyond reach, and Japan says it is premature to commit to 2020 limits. Developing nations are clamoring for commitments by rich countries before they discuss what poorer countries should do.

Environmentalists were disappointed with yesterday's announcement. "Kobe gave ministers the opportunity to accelerate the slow progress of G8 climate negotiations, but they failed to send a signal of hope," said Naoyuki Yamagishi, head of the Climate Change Program at WWF Japan.

The United States, the top greenhouse-gas emitter in the G8 and the only leading industrialized nation that has not ratified the Kyoto Protocol, argued that midterm goals were too sensitive to be set without long negotiations.

Scott Fulton, deputy assistant administrator at the U.S. Environmental Protection Agency, called for commitments from heavily polluting emerging economies. He also defended U.S. action on climate change, citing billions of dollars spent on environmental research and other steps against global warming.