* Major economies consider setting "aspirational" goal

* Halve emissions by 2050, 80 pct cut for rich nations

OSLO, June 25 (Reuters) - Major economies including the United States and China are considering setting a goal of halving world greenhouse gas emissions by 2050 when they hold a summit in Italy next month, a draft document showed.

The draft conclusions for the Major Economies Forum, a group launched by President Barack Obama to contribute to a new U.N. climate treaty, were tabled by the United States and Mexico at talks in Mexico this week, without reaching agreement.

"We support an aspirational global goal of reducing global emissions by 50 percent by 2050, with developed countries reducing emissions by at least 80 percent by 2050," according to the draft text, obtained by Reuters.

The two-page text also said that developed countries, including the United States, the European Union and Japan, would take "robust aggregate and individual mid-term reductions in the 2020 timeframe."

And it said that developing nations would have to take actions by 2020 that meant a "significant deviation from business as usual" to slow a rise in their emissions, mainly from burning fossil fuels, while working to end poverty.

Last year rich nations in the Group of Eight agreed a "vision" of halving world greenhouse gases by 2050. That goal was not adopted by developing countries, which have argued that the rich have to take the lead.

Leaders of the 17-nation Major Economies Forum will meet on July 9 in Italy on the sidelines of a G8 summit to try to find ways to slow warming which may bring more floods, droughts and rising sea levels.

The major economies account for 80 percent of all emissions and an agreement among them would go a long way to settling a U.N. climate treaty due to be agreed in Copenhagen in December.

"The peaking of global and national emissions should take place as soon as possible, recognising that the timeframe for peaking will be longer in developing countries," it said.

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