South Korea's air carriers have again agreed to reduce their greenhouse gas emissions as part of national efforts to fight climate change, the government said Friday.

The voluntary agreement is the third of its kind signed by the country's seven airlines, including flag carriers Korean Air and Asiana Airlines, according to the Ministry of Land, Transport and Maritime Affairs.

"Under the first agreement signed in 2010, the companies reduced their use of fuel by 166,000 tons and greenhouse gas emissions by 524,000 tons," the ministry said in a press release.

Efforts to cut emissions of greenhouse gas, such as carbon dioxide, include improving the fuel efficiency of aircrafts.

Such efforts will entail purchasing new and lighter aircraft that are more fuel-efficient, as well as making the aircraft's equipment lighter, the ministry said.

South Korea pledged in 2009 to voluntarily cut its greenhouse gas emissions by 30 percent from the business-as-usual levels in 2030, even though the country is not required to do so under any international agreement. (Yonhap News)