WESTERVILLE, Ohio - Police arrested a 16-year-old accused of saying he was going to blow up a high school - the seventh student charged with making a bomb threat at one of the schools in the suburban Columbus district in the past two school years.

Police Lt. Joe Morbitzer said yesterday that he does not believe the student was linked to the previous two bomb threats at Westerville South High School this year.

''We've spoken to the student,'' Morbitzer said. ''It doesn't appear he's tied into the other two.''

The district banned backpacks at the school after the first threat was found on a boys' bathroom wall Sept. 17. The ban was lifted today, but reinstated through the end of this week after another threat was found on a girls' bathroom wall, district spokesman Mark Hershiser said.

Morbitzer said there have been 13 threats at five district schools in the past two school years.

He said maintaining a safe learning environment is the district's top priority.

''We're definitely taking a hard line on this. Zero tolerance,'' he said.

''Everybody is frustrated and everyone is working together,'' Hershiser said.

The student, whose name was not released, was suspended from school for 10 days pending an expulsion hearing before the superintendent, Hershiser said.

Morbitzer said a teacher heard the student say he was going to blow up the school.

The student was charged as a juvenile with inducing panic, a felony that could keep him in custody of the Department of Youth Services until he is 21, Morbitzer said.