JUNEAU -- Alaska Gov. Sean Parnell has signed into law a bill that bans synthetic cannabinoids.

House Bill 7 criminalizes possession of less than 12 grams of the drug as a misdemeanor, and possession of more than that amount as a felony.

The ban takes effect July 1.

The substances are designed to mimic marijuana and are undetectable by most drug tests. They have been credited with causing side effects like nausea, hallucinations and panic attacks.

Parnell's spokeswoman said he signed the bill Thursday.