A group of radical artists who panicked viewers of a Czech TV station by sneaking a nuclear mushroom cloud into its weather report are to be put on trial, prosecutors confirmed yesterday.

Six members of the Ztohoven collective, whose aims include "penetrating public space", are to appear in court this month charged with spreading false information. They could face three years each in jail.

The artists sent shock waves through the Czech Republic in June last year by splicing footage of the atomic explosion into a live panoramic shot of the Krkonose mountains, in north-east Bohemia.

The fake blast prompted panicked calls to the switchboard of the TV channel CT2, with some viewers fearing that a nuclear war had begun while others suggested there had been a gas explosion.

The impact of the broadcast was compared to Orson Welles' War of the Worlds radio broadcast of 1938, in which listeners were led to believe that Martians were invading Earth. Listeners who took it to be a news broadcast panicked, and several suffered heart attacks.

In the Czech broadcast viewers saw their screens obscured by a flash of bright light after which an orange fiery mushroom cloud ascended on the horizon.

Ztohoven said the aim of its project, which it called Media Reality, was not to harm, but to illustrate how the media manipulates reality.

In a statement it said: "We are neither a terrorist organisation nor a political group. Our aim is not to intimidate society or manipulate it, which is something we witness on a daily basis both in the real world and that created by the media. On June 17 2007, [we] attacked the space of TV broadcasting, distorting it, questioning its truthfulness and its credibility."

The group added that they hoped their action would "remind the media of their duty to bring out the truth".

But Martin Krafl, spokesman for the TV channel, called the hijack irresponsible. "The fake broadcast was really very inadvisable and could have provoked panic among a wide group of people," he said.

Ztohoven, which in Czech means variously "out of it" and "a hundred shits", has made a name for itself with a series of other artistic happenings, such as its attempts to cover up a neon heart which had been placed on top of Prague castle to mark the end of Vaclav Havel's presidency in 2003. It also covered up hundreds of street lamps and neon signs in Prague to protest against the unchecked proliferation of advertisements in the post-communist Czech Republic.

Ztohoven's fake broadcast secured mainstream recognition for the first time last month, when it was awarded the Czech National Gallery's newly established £9,000 young artists' competition.

See video footage of the hoax at youtube.com/watch?v=MzaN2x8qXcM