The French justice system has scored a series of major victories in high-profile corruption cases against right-wing politicians, but the successes have sparked claims of bias and verbal attacks on prosecutors and judges.

After the stunning conviction of ex-president Nicolas Sarkozy this week, a debate has raged about whether the sword of justice is getting stronger, or whether its blows are being manipulated.

Sarkozy, who became the first modern president sentenced to jail, has consistently sought to portray the multiple investigations into his affairs since leaving office in 2012 as a witch hunt.

Former French president Nicolas Sarkozy has claimed bias in the justice system after his conviction for influence peddling
Former French president Nicolas Sarkozy has claimed bias in the justice system after his conviction for influence peddling AFP / Ludovic MARIN

He has called it a "scandal that will remain in the annals of history," has questioned whether France still lives under the rule of law, and suggested that the tactics of investigators are reminiscent of those in "Mr Putin's Russia."

When asked for his reaction in a prime-time television interview on Wednesday, the 66-year-old said he was "used to suffering this harassment."

Sarkozy's influence-peddling conviction follows the sentencing last June of his ally and long-time prime minister Francois Fillon, who was found guilty of giving fake parliamentary jobs to his wife.

Fillon, whose presidential campaign was derailed by the allegations in 2017, once accused magistrates of conspiring in a "political assassination".

Former prime minister Francois Fillon was convicted in a fake jobs scandal that imploded his 2017 presidential campaign
Former prime minister Francois Fillon was convicted in a fake jobs scandal that imploded his 2017 presidential campaign AFP / Thomas SAMSON

On Thursday, it was the turn of former defence minister Francois Leotard, who said he was "ashamed of the French justice system" after he was found guilty of organising kickbacks in defence deals in the 1990s.

The attacks, particularly by Sarkozy and his allies, led Justice Minister Eric Dupond-Moretti this week to worry about the "shouting" and what he called the "mistrust" of the justice system.

And Sarkozy's successor as president, Francois Hollande, said Saturday that he "cannot accept these repeated attacks on the judiciary and its independence".

Already in France, less than one in two people (48 percent) express confidence in the justice system, according to an annual survey by the Cevipof political institute at Sciences Po university in Paris.

Trust in France's justice system has dropped below 50 percent even as it scores high-profile convictions against top politicians
Trust in France's justice system has dropped below 50 percent even as it scores high-profile convictions against top politicians AFP / JACQUES DEMARTHON

Much of the "shouting" has been directed at the National Financial Prosecutors' office (PNF), a specialist anti-corruption agency set up in 2014 to prosecute fraud and white-collar criminals.

UBS had to pay a fine of almost four billion euros in 2019 for encouraging clients to commit fraud
UBS had to pay a fine of almost four billion euros in 2019 for encouraging clients to commit fraud AFP / Fabrice COFFRINI

In the seven years since, it has become one of France's most fearsome prosecution services after pursuing Sarkozy, Fillon and Sarkozy's top confidant Claude Gueant.

They have all been convicted, but will appeal.

Others brought to book by the PNF include the right-wing mayor of a wealthy suburb of Paris, Patrick Balkany, who was found to have used offshore accounts and hidden luxury villas from tax authorities.

Some of the criticism relates to the PNF's choice of targets -- the most prominent recent cases involve right-wingers -- while others have questioned its methods, which include extensive wiretapping.

Jean-François Bohnert heads France's PNF anti-corruption prosecutors and says they have recouped 10 billion euros for the state since the agency was set up
Jean-François Bohnert heads France's PNF anti-corruption prosecutors and says they have recouped 10 billion euros for the state since the agency was set up AFP / Eric Feferberg

"Politicised justice is something from other countries, other geographic spheres," the PNF director Jean-Francois Bohnert said this week when asked about the accusations of bias.

"The PNF does not do politics, the PNF does not deal in political crimes: the PNF deals with economic and financial crimes," he said.

Defenders of the office point out that it was set up by a Socialist government to prosecute one of its own: former budget minister Jerome Cahuzac, who was found to be hiding cash in a Swiss bank account.

The PNF's work goes far beyond pursuing prominent politicians, who form a small minority of the 605 cases currently overseen by its team of 17 specialised magistrates.

Many cases involve foreigners, including the playboy son of the long-time leader of oil-rich Equatorial Guinea; former global athletics chief Lamine Diack; and figures involved in the awarding of football World Cups to Qatar and Russia.

In 2017, the PNF negotiated a 300-million-euro ($360 million) payout from the Swiss arm of British bank HSBC, and it secured a 3.7-billion-euro fine from Swiss bank UBS in 2019, for encouraging clients to commit fraud.

Since its creation, the office "has brought back to state coffers the rather large sum of 10 billion euros through its confiscations and fines," Bohnert told RTL radio on Tuesday.

Tom Burgis, author of the recent book "Kleptopia: How Dirty Money Is Conquering the World", says "the standard first move" from the corrupt is to try to undermine their investigators.

He told AFP that financial and political backing for institutions like the PNF was essential in developed democracies.

"They are on the frontline, but they are generally spectacularly underfunded," he said.

Prosecutions of French politicians -- and allegations of bias -- pre-date the creation of the PNF.

Late right-wing president Jacques Chirac and former prime ministers Alain Juppe and Edith Cresson were all convicted.

But some fear that although the PNF looks at its strongest following its success against Sarkozy, it is highly exposed with its credibility on the line.

If the ex-president succeeds in overturning his conviction, the PNF's reputation and the justice system more broadly would take a serious blow.

Le Monde newspaper wrote on Tuesday that the office "comes out reinforced by the verdict of the court (against Sarkozy), without being completely certain about the future."