Qatar and Royal Dutch Shell have agreed to develop liquefied natural gas as fuel for use by the world's largest container shipping company, A.P. Moller-Maersk, Qatargas said in a statement on Monday. Qatargas, the world's largest LNG producer, said the three companies signed a memorandum of understanding that sees Qatargas 4, a joint venture between Qatar Petroleum and Shell, producing the fuel for use by Maersk Line, Reuters reported. Most shipping companies currently use heavy fuel oil, or bunker fuel, to propel their vessels although LNG as marine fuel has been used by some ships in the past decade. DNV GL, an international energy and shipping certification agency, says while most of the industry will continue to use heavy fuel oil for now, LNG is being used more, in part because it more easily meets current and proposed emission rules. "This cooperation between Qatargas, Maersk Group and Shell represents an important step in developing LNG as a viable fuel for maritime transportation," Maersk's chief executive, Nils Smedegaard Andersen, said in a statement.