A 14-year-old boy has been charged with making threats to kill after a Geelong mosque received a series of violent and concerning messages online.

Police are investigating the messages which were directed towards a mosque in the suburb of Manifold Heights at the weekend, around the same time mosques across the state opened their doors to the public for the annual Open Mosque Day.

A series of online threats have been made against the Geelong mosque. Credit:Nine News

The boy, from a suburb in Geelong, was arrested and charged by investigators from the counter-terrorism command and bailed to appear at Children's Court at a later date.

The threats came in the wake of the massacre at mosques in Christchurch, which killed 50 innocent worshippers.