A SECURITY alert forced emergency services to seal off part of the Royal Mail depot in Tonbridge today after staff discovered an unidentified white power in a sorting machine but the substance turned out to be harmless.

The depot, in Vale Rise, was sealed off just before midday and staff due to finish their shifts were told by police that they unable to leave the premises.

Police said the alert was called off at about 3pm and staff were allowed to work normally. Royal Mail were reluctant to comment on the matter.

The same depot was evacuated in May after white powder was found leaking out of an envelope. On that occasion it turned out to be powdered baby milk.