Eleven Somali nationals accused in separate pirate attacks on U.S. Navy ships off Africa have pleaded not guilty in Virginia to a new indictment.

The U.S. attorney's office said the defendants entered their pleas on Wednesday to new charges that were in an indictment filed earlier this month.

Six of the men are accused in the April 10 attack on the USS Ashland. Five are charged with an alleged April 1 attack on the USS Nicholas. The Virginia-based ships were patrolling pirate-infested waters off Africa.

If convicted of a piracy charge, the suspects would face a mandatory life term.

An October 19 trial date was scheduled for the Ashland defendants, while a November 9 trial was scheduled for those accused in the alleged Nicholas attack.