SANTIAGO (Reuters) - A freight train in southern Chile was derailed and some of its cargo units burned by unknown assailants on Tuesday, officials said, amid tensions between the state and the local Mapuche indigenous group demanding the return of ancestral lands.

       The attack on the train, which had been carrying cellulose used to make paper, happened in the South Macrozone area of Victoria, which has been under a state of emergency due to the conflict.

       "We have burned machinery and locomotive cars that transported cellulose from Valdivia to the Concepcion area," Victor Manoli, presidential delegate to the area, told reporters. Images of the derailed and still smoking wagons circulated on social media and local TV.

       "We must recognize that what we are experiencing today are acts of terrorism," Manoli added.

       The official said that so far no one had claimed responsibility for the attack, which caused a suspension of train service from the town of Victoria and Temuco to the regional capital of La Araucania.

       La Araucania is home to Mapuche communities that are reclaiming lands that have been turned over to companies in the forestry sector. In recent years, sabotage has increased in the region with the burning of houses, trucks and machinery.

       (Reporting by Fabian Cambero, writing by Hugh Bronstein; Editing by Marguerita Choy)