British teachers were given the power to confiscate killer drug meow meow, The Sun reported Saturday in the wake of its campaign against the chemical.
The government's schools minister Vernon Coaker said Friday that teachers would not have to return the drug to pupils.
On Thursday, teachers who seized the drug were handing it back after school - because it is legal.
Louis Wainwright, 18, and Nicholas Smith, 19, died Monday in Scunthorpe, eastern England, after taking it.
A 26-year-old man arrested over the two teenagers' deaths was bailed Friday.
After dithering for days, Coaker wrote to every principal in England, saying, "Schools do have the power to confiscate inappropriate items, including a substance they believe to be mephedrone (or any other drug whatever its legal status). They do not have to return such confiscated substances."
The National Association of Headteachers' general secretary Mick Brookes welcomed the intervention saying, "Today's clarification is absolutely vital."
Coaker also backed a government ban. A report was expected to go to ministers at the end of the month, but a ban was unlikely to happen until the summer.
More than one in thirteen students at Cambridge University admitted in a survey to taking meow meow.