A passenger train running solely on biogas, billed as the world's first, was unveiled in Sweden yesterday, in what officials called a major step toward making public transport more environmentally friendly.

　　The train, which is fitted with two biogas bus engines, was started up and rolled for a few meters on the tracks at the train station in Linkoping in south-central Sweden, officials said in a statement.

　　It can carry up to 54 passengers and is expected to start running on an 80-kilometer stretch between Linkoping and Vastervik on the country's east coast starting in August or September.

　　Biogas is produced by decomposing organic material in an oxygen-free environment, and emits just a small fraction of the carbon dioxide released by diesel engines.

　　The train can run for about 600 kilometers on a full tank and has a top speed of 130 kilometers per hour.

　　(The Associated Press)