HANOI, Vietnam (AP) — State media say a Vietnamese-American pro-democracy activist has been arrested and accused of terrorism for allegedly trying to sabotage liberation celebrations commemorating the end of the Vietnam War.

The Tuoi Tre newspaper says 58-year-old Nguyen Quoc Quan was detained April 17 after arriving at the airport in southern Ho Chi Minh City. He is accused of planning to hold protests for Viet Tan, a banned U.S. exile group, during May Day festivities and the anniversary of the fall of the former U.S.-backed South Vietnamese capital, Saigon, on April 30, 1975.

The paper says authorities also found many documents in Quan’s possession on terrorist training.

The U.S. government has said it has seen no evidence that Viet Tan is a terrorist organization.