NASHVILLE (Reuters) - Tennessee's governor has signed into law a measure allowing teachers to be penalized for promoting or condoning so-called "gateway sexual activity" by students, expanding the state's existing abstinence-based sexual education program.

"The bill language and provisions are generally in line with our current standards and law," said David Smith, a spokesman for Republican Governor Bill Haslam.

The gateway activity in question remains vague. Some critics have said it could punish teachers for allowing students to hug or hold hands. The bill has been ridiculed by television comedian Stephen Colbert.