Geneva - A Swiss amateur astronomer has discovered a new comet from an observatory in the western Jura district, the ATS news agency said Saturday.

Only five similar comets -- fragile clusters of dust, ice and carbon-based molecules believed to be primitive material left over from the building of our star system -- have been been documented from Switzerland since the 17th century.

The latest one to be discovered has a diameter of 20,000 kilometres (12,400 miles) and has been named Ory after Michel Ory who made the discovery, the report said.

Discovered from the Vicques Observatory in Jura, Ory spotted the comet overnight from Tuesday to Wednesday and again from Wednesday to Thursday.

The best sightings are expected in October and November, the report added.

Some 200 comets are currently documented, the most famous of which is Halley's Comet.

Ory has already discovered some 50 asteroids.