A statement from City of London Police said:
The Old Bailey has been evacuated following the discovery of a suspect package.
City of London police officers are at the court. One man has been detained while further checks are carried out.
Significant road closures are in place around the court.
The spokeswoman would not comment on reports the suspect package was found in Court 11, where Pavlo Lapshyn in being sentenced for bombing three mosques, and murdering a Muslim pensioner in a series of racist attacks.
More top news
Jeremy Corbyn has denied allegations of bullying saying "intimidation is not allowed" in the Labour party.
A gunman who killed nine people and at a Munich shopping centre was German-born and had no links with Islamic State, authorities say.
Torrential rain and flooding has killed 24 people in China and forced tens of thousands from their homes, according to state media.