"Deplorable" and "irritating" are two of the milder adjectives used by European Central Bank policymakers to describe the debate over when Wim Duisenberg will step down as ECB president and who will succeed him.

Combining elements of high-level intrigue, political posturing and a potential whiff of scandal, it is a saga that illustrates how national power-broking is never far from the heart of any project to do with European integration.

It all began in November 1997 when President Jacques Chirac of France out of the blue announced he would nominate Jean-Claude Trichet, governor of the Bank of France, to be the first ECB president.

The announcement stunned his fellow European Union leaders, who had been carefully building a consensus around the nomination of Mr Duisenberg, who was already sitting as the head of the preparatory European Monetary Institute.

Eventually, a messy compromise was reached in May 1998 under which Mr Duisenberg was appointed on the understanding that he would "voluntarily" step down before completing his full eight-year term. Everyone was led to believe that Mr Trichet would succeed him.

Ever since then speculation has raged about when Mr Duisenberg might retire and whether Mr Chirac really secured a firm promise from Germany and other EU countries that the successor would be French. The suggestion that France has an automatic right to the presidency holds little appeal for some EU countries, notably Mr Duisenberg's native Netherlands, which was deeply offended by Mr Chirac's gambit.

Mr Duisenberg delivered his latest word on his own position on October 11, saying he thought it would be unwise to change the ECB leadership over the next 12 months.

Some officials close to the ECB's 18-member policymaking governing council say this should not be taken as a sign that the president, whose term would normally expire in May 2006, is planning to retire next October or even soon afterwards. "The truth is, it's in his own head. No one knows," one official says.

Mr Duisenberg's remark was nonetheless significant because it implied he would be in office after France's presidential and parliamentary elections, which will be held between April and June next year. Depending on the outcome of the elections, the French might be more or less aggressive in pressing for Mr Duisenberg's departure.

It also implied he would still be in place after the expiry next May of the four-year term of Christian Noyer, his deputy, whom some see as a possible alternative to Mr Trichet as his successor.

Uncertainty over the succession intensified in May 2000 when Mr Trichet revealed that he was the subject of a French judicial investigation into his role in the collapse of Credit Lyonnais, a state-owned French bank, in the early 1990s.

So far, there is nothing to suggest that Mr Trichet will fail to clear his name. But in the event that the case proceeds to trial, or that the investigation drags on indefinitely, it would be politically difficult for France to nominate Mr Trichet.

Hence the need for an "insurance policy", a reserve candidate who is both French and a credible central banker. Mr Noyer appears to fit the bill. Certainly, his ECB colleagues regard him as a man of integrity and independence, someone who is by no stretch of the imagination a puppet of Paris politicians.

However, the EU's Maastricht treaty states that the ECB's six executive board members, who include Mr Noyer, are selected for non-renewable terms.

This may not prove an impossible hurdle to overcome. Senior ECB officials have taken legal advice on whether a board member could serve his full term and then switch to a different job - in Mr Noyer's case, the presidency. So far, the lawyers are thought to be divided on the issue.

For his part, Mr Noyer is said to oppose any violation of the treaty's spirit and to be ready to step down as ECB vice-president at the end of May. If he does so, it may well suit France's political establishment, for Mr Noyer's departure would leave France without a representative on the ECB's executive board, a gap that could be filled only if a French candidate inherited the ECB presidency.

One solution, not favoured inside the ECB, is that EU governments will pick a candidate who is not currently on the bank's council. This idea was in the air earlier this year, when Jean-Claude Juncker, Luxembourg's prime minister, said he had been approached about taking the presidency.

Mr Juncker said he had turned down the suggestion and is said later to have regretted making the disclosure. "One thing is clear. The next ECB president will come from within the governing council," says one ECB official.

A senior French official at the ECB agrees: "The culture of many of our partners pushes them to let the choice be made inside the governing council."

Additional reporting from Paris by Martine Royo of Les Echos