The Yorkshire Evening Post understands the package containing white powder was mailed to judge Geoffrey Marson, QC, the man who previously jailed Stephen Yaxley-Lennon - who calls himself Tommy Robinson.
Emergency services were called to the court on Oxford Row at 11.44am today over reports of the delivery of a "suspect item of mail".
Police, fire and ambulance incident response units attended the building on Oxford Row in Leeds city centre. The building was not evacuated and many of the courts continued to function as usual. The package was delivered to the court's general office and was secured pending an investigation.
A West Yorkshire Police spokesman confirmed the item has now been deemed safe.