What is this investigation about?

This is one of a number of investigations still going on from a long-running scandal at City Hall when Jacques Chirac was mayor of Paris from 1977 to 95. About 30 former members of city council staff and Gaullist party officials have been convicted in three different cases. Alain Juppe, his deputy at City Hall who later became prime minister, was given a 14-month suspended prison term in 2005 for his role in the illicit finances affair. Chirac himself was protected from questioning, or prosecution, during his time as president.

What are the allegations against Mr Chirac?

When he was mayor he was in charge of both the city council and his RPR party at a time when it creamed off millions of pounds from contracts in various areas, for example the building of schools and council houses. But the only aspect of the investigation in which Mr Chirac is alleged to be personally implicated is over the granting of "fake" city jobs to Gaullist officials. The only single piece of evidence which specifically links him to it is a letter he signed in 1993 telling the council to give a salary to a secretary who was working for the party full time.

What is the significance of Mr Chirac being questioned as an "assisted witness"?

That means that he may be charged down the line - he is more than a simple witness and becomes a potential suspect. But it was Mr Chirac himself who sought this status, because it gives his defence lawyers stronger access to the dossier, to questioning by judges and so on.

So is he in trouble?

The chance that Jacques Chirac will ever be convicted of anything are thought to be extremely slim. The statute of limitations has expired for many of the offences allegedly committed in his mayoral years - even though the clock was stopped during his 12 years of presidential immunity - and French justice is extremely slow. It can take years for cases to come to court. Nobody expects this case to move any quicker.

Presumably, Nicolas Sarkozy has a say in what happens?

President Sarkozy can pardon anyone he wants, although it's unlikely to get to that. And although the examining magistrates are notionally independent, the Government controls the Justice Ministry. There is no American-style independence of the judiciary here, none of the same checks and balances. There is no sign that anyone senior wants to go after Chirac.

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