A package containing explosives was discovered at a Jehovah's Witness meeting in Kalsdorf in Austria,  near the southern city of Graz, police said in a statement on Saturday.

With around 50 people at the hall, officials said the device could have "potentially caused great damage."

What police have said

A suspicious package was discovered at the entrance of the building which led to an emergency call being made at 8:30 p.m. (1930 UTC/GMT) on Friday.

When police arrived, a security cordon was established to recover the package in an operation which police said lasted the night.

Specialized teams used X-ray machines and a robot to help determine the type of threat presented.

Following a thorough investigation, a police spokesman said on Saturday: "It is an unconventional, homemade, but basically functional explosive device."

Police said state security was investigating, but there was no initial information about possible perpetrators or a motive.

Additional protective measures have been put in place at all Jehovah's Witness properties and police have appealed for the public to report any suspicious sightings or objects immediately.