BRUSSELS

The powder letter discovered on Wednesday at a mail processing facility for the US Embassy in Belgium has been confirmed harmless, the Halle‑Vilvoorde Prosecutor's Office said on Thursday.

Authorities said the powder was analyzed by the Civil Protection service and found to be a mixture of pharmaceuticals, including ibuprofen, with no toxic or dangerous substances, according to broadcaster VRT.

The letter was discovered on Wednesday afternoon in a storage area on Fabrieksstraat in Zaventem, where all mail addressed to the US Embassy is sorted and screened.

The facility is equipped with a special screening booth and extraction system.

One employee who came into contact with the envelope was immediately placed in quarantine as a precaution.

The prosecutor confirmed that the quarantine for the individual has since been lifted following the negative results.

The source and sender of the powder letter remain under investigation.