Renault say they are launching legal action against Nelson Piquet Jr and his father Nelson Piquet over race-fixing allegations made against the team.

The team are accused of plotting with Piquet Jr to crash during last year's Singapore Grand Prix to aid team-mate Fernando's Alonso's path to victory.

Renault says the criminal proceedings being launched in France concern "the making of false allegations".

They also refer to a "related attempt to blackmail the team".

The French team says that the blackmail attempt was in relation to "allowing Mr Piquet Jr to drive for the remainder of the 2009 season," according to a statement released by them on Friday.

Piquet Jr was dismissed by Renault in early August.

Renault - who are also referring the matter to police in the UK - are to attend an extraordinary meeting of motorsport's governing body, the FIA, on 21 September to answer the race-fixing allegations made against them.

If found guilty, the team could face severe sanctions which could include expulsion from the current F1 world championship.