A 16-year-old arrested on suspicion of terror offences has been released after an "unknown substance" found in his possession proved to be non-hazardous.
A raid was carried out at the boy's west London home on 29 August, when officers found cannabis plants and an imitation firearm.
The boy was later arrested under the Terrorism Act after the substance was also found.
He was released under investigation on Monday evening, police said.
Scotland Yard confirmed the substance had been found to be "non-hazardous" following analysis.