France on Thursday ordered its top anti-terrorist unit to investigate after the judge in charge of a corruption probe into former president Nicolas Sarkozy was sent bullet cartridges and death threats in the post.
The probe will also examine similar missives sent to two journalists, police said, as a bitter row over the independence of France's judiciary escalated.
Jean-Michel Gentil, the most prominent of three examining magistrates investigating Sarkozy, was warned that his family or colleagues could be targeted in a letter received at his office on Wednesday, six days after he placed the former right-wing leader under formal investigation on suspicion of corruption.
"You are physically protected but someone close to you is going to disappear," the letter stated, denouncing Gentil as a "red judge".
Jean-Pierre Elkabbach, a veteran commentator for Europe 1 radio and one of the best-known journalists in France, received a similarly worded threat last week, as did Michael Darmon of television news channel iTele.
"The letter I got said 'this time the bullet is blank, the next time it won't be'," Elkabbach said.
Organisations representing magistrates said the threats against Gentil were the result of a climate in which politicians consider themselves free to attack judges' decisions, often in virulent terms.
"There is an obvious direct link," Virginie Duval of the biggest magistrates organisation, the USM, told AFP. "This is what happens when certain politicians consider themselves permitted to criticise and insult."
The smaller magistrates' union, SM, pointed the finger at Sarkozy's inner circle.
"The violence of their statements and the attempts they've made to discredit the legal process has inevitably led to the unacceptable unleashing of hatred towards magistrates charged with seeing justice is done," the SM said in a statement.
Gentil has been accused of being politically motivated by a number of Sarkozy supporters as well as by the former president's own lawyer, Thierry Herzog, who is seeking to have the charges against his client dismissed.
The row has become so poisonous that Justice Minister Christine Taubira has asked the CSM, the council that overseas magistrates, to give an opinion on the politicians' conduct. Sarkozy said Thursday his appeal against the charges would be suspended until that had been issued.
Henri Guaino, a lawmaker and former special adviser to Sarkozy who said earlier this week that Gentil's conduct had "dishonoured justice", was standing by his comments on Thursday.
But they have been widely condemned by lawyers, who point out that investigative judges have proved themselves just as willing to examine alleged wrongdoing by politicians on the left of the political spectrum.
Socialist Budget Minister Jerome Cahuzac resigned last week after a judge announced he would extend a preliminary probe into a Swiss bank account he allegedly used to hide assets from the tax authorities.
The case against Sarkozy is at a more advanced stage with the former president having been placed under formal investigation for alleged abuse of someone weakened by illness.
Under French law, this is the equivalent of being charged in other legal systems but does not mean the case will necessarily end in a trial.
Sarkozy denies allegations that he accepted cash-stuffed envelopes from France's richest woman Liliane Bettencourt to fund his successful 2007 campaign. The L'Oreal heiress has suffered from dementia since 2006.
If convicted of taking advantage of her, Sarkozy faces up to three years in jail, a fine of 375,000 euros ($480,000), and a five-year ban from public office.
That would wreck his hopes of a political comeback and the latest opinion polls suggest that prospect is already receding. In a survey published Thursday, 54 percent of voters said they did not regret his exit from national politics.