SIOUX FALLS, S.D. (AP) - Two South Dakota men facing sex trafficking charges in federal court have pleaded not guilty to additional charges.

The Argus Leader newspaper in Sioux Falls reports (http://argusne.ws/Xbbou8 ) that the new charges follow unsuccessful attempts by defense lawyers for 36-year-old Carl Campbell and 35-year-old Tajahn Clinton to withhold evidence of alleged online sex trafficking discovered on computers and cellphones seized by authorities.

Clinton was indicted in February, and Campbell in April. Both could face life in prison if convicted.