Venezuela’s top prosecutor has ordered the arrest of a dozen opposition members. Attorney General Tarek William Saab on Wednesday accused them of conspiring against a referendum the government held Sunday to claim sovereignty over a large swath of neighboring Guyana.

CARACAS, Venezuela (AP) — Venezuela’s top prosecutor on Wednesday ordered the arrest of a dozen opposition members, including former National Assembly leader Juan Guaidó and three campaign staffers of presidential candidate Maria Corina Machado.

Attorney General Tarek William Saab accused them of conspiring against the referendum the government held Sunday to claim sovereignty over a large swath of neighboring Guyana that Venezuela has long argued was stolen when the border was drawn more than a century ago.