A leading Georgian opposition party Sunday said it was preparing a lawsuit against a television channel over a fake news report about a supposed Russian invasion and murder of President Mikheil Saakashvili.

The lawsuit will be prepared by the Democratic Movement-United Georgia party led by ex-parliamentary speaker Nino Burdzhanadze and filed against the private Imedi TV channel, which showed the footage Saturday evening.

'The lawyer has been working over the lawsuit since yesterday (Saturday) and will be brought to a court of law soon. This will be a criminal lawsuit as Imedi's actions have gone beyond administrative offences,' Khatuna Ivanishvili, a spokeswoman for Burdzhanadze, told RIA Novosti.

The broadcast, which used the channel's normal news graphics, began with a warning that the programme showed a sequence of possible events that could occur 'if Georgian society is not brought together against Russia's plans'.

The news item included clips of panicked residents trying to flee Tbilisi and reported that there was panic in Gori, Mtskheta and other regions.

The staged images and words rang true, however, when viewers who did not see the introduction took the report at face value. People from all over the country began to call each other and the TV studio to find out what was really happening.

The demonstration of the report, intended to illustrate a studio discussion on the chance of a fresh conflict between Russia and Georgia, forced the Georgian authorities to calm public fears.

'I can say with confidence that, on the declaration of the president, real danger, which was imagined in the transmission...does not currently exist for our country,' a spokeswoman for President Mikheil Saakashvili said.

Imedi TV admitted that the report 'caused a big concern among the citizens'.

Russia's envoy to NATO, Dmitry Rogozin, called the TV channel's stunt 'criminal' and declared that in the wake of Friday's meeting of the NATO-Georgia council it should show the military alliance not to deal with Saakashvili.

Former Georgian republics, Abkhazia and South Ossetia, which Russia recognised as independent in August 2008 after its forces repelled a Georgian attack on the latter republic, have also dismissed the broadcast.