France's most politically charged trial in years is under way with former prime minister Dominique de Villepin accused of plotting to smear Nicolas Sarkozy before he became president.

Mr de Villepin is accused of having created fake evidence of corruption against Mr Sarkozy in the lead-up to the 2004 elections, when both men were hoping to win the right-wing party nomination and succeed President Jacques Chirac.

The trial, due to run for a month, will focus on the biggest political scandal France has seen in years.

The French are calling it the trial of the decade. A number of big names in politics and industry are set to give evidence: President Sarkozy is a civil plaintiff in the case.

The trial of the so-called ‘Clearstream affair’ is shaping up as a showdown between Mr de Villepin and President Sarkozy, whose rivalry is legendary in French political circles.

Mr de Villepin is accused of complicity in slander and in use of forgeries, dealing in stolen property and breach of trust.

He has denied any wrongdoing, but if convicted he faces up to five years in jail and a €45,000 fine.

Mr de Villepin accuses Mr Sarkozy of being obsessed by the case and argues that the president's involvement in the trial as a civil plaintiff has distorted proceedings.

'I am here because of one man's decision and one man's obsession,' he said as he arrived at the courthouse with his wife and three children.

'I will emerge free and with my name cleared,' he added.

The month-long hearings before the Paris criminal court could also cast light on the murky dealings of French intelligence and at one of the world's top aerospace companies, EADS.