PARIS, June 26 (Reuters) - French prosecutors said on Friday that the anti-terrorist police branch was deployed to investigate an attack which left one person dead and several wounded in southeast France.

A probe has been opened for murder and attempted murder in an organised group in relation to terrorism, the Paris prosecutor's office said in a statement.

French media said a decapitated head was found at the site, along with a flag bearing Islamist inscriptions.

A police source said he could not confirm the decapitation but said it seemed as though this was the case. One suspect had been arrested, a local official told BFM TV. (Reporting by Dominique Vidalon; Editing by James Regan)