contain pollutants that help cause global warming. But a final U.S. decision on adoption of international standards is likely to be left to the next presidential administration. EPA officials said at the time that the earliest the agency is likely to propose adoption of ICAO standards would be in 2017. Boeing is the United States' largest exporter as measured in dollar value. The company vies with Airbus for the title of world's largest aircraft maker. Aviation accounts for about 5 percent of global greenhouse emissions, according to environmentalists. ICAO says it's actually less than 2 percent. But that share is expected to grow as aviation grows. "We also recognize that the projected doubling of global passengers and flights by 2030 must be managed responsibly and sustainably," said Aliu.

President Juan Manuel Santos on Monday said a referendum would be held on a possible peace deal with Marxist FARC fighters, whether the rebels want a vote or not.

The FARC and the government have said they aim to sign a peace deal by March 23.

"Whatever gets signed in Havana, I will submit to a referendum vote, whether the FARC likes it or not," Santos said in a Twitter post.

The FARC's lead negotiator Ivan Marquez earlier in the day had said he was opposed to the idea.

The talks, held in Havana, are believed to be nearing a long-sought deal to end Latin America's longest-running insurgency.

Colombia's biggest rebel force, the now 7,000-strong FARC has been fighting the government in Bogota for five decades.

Last week, the United States pledged $450 million to fund Colombia's peace process -- if a deal is indeed signed to end the war that has left more than 220,000 people dead and displaced six million others.

Once a virtual failed state, Colombia is increasingly seen as a pivotal player in Latin America and one of the region's most dynamic and democratic countries.

AFP