Claims by a former close confidant of Monaco's royal family that part of its fortune is placed in tax havens have rocked the affluent city state, in the latest scandal facing the palace under Prince Albert II.

The new controversy erupted after French newspaper Le Monde last week published the allegations, which it said were based on detailed notes the palace's wealth manager made while working for the family.

Claude Palmero was for more than two decades in charge of managing the palace's assets, first for Rainier III, the husband of American actress Grace Kelly, and then their son Prince Albert when he became ruler of Monaco in 2005.

But the wealth manager, who took over from his father in 2001, was unexpectedly forced to step down last year, and he has since tried to sue the monarch over his dismissal.

Le Monde reported that, according to five books of notes Palmero took with him when he left the palace, some royal funds have been placed offshore over the years in the tax havens of Panama and the British Virgin Islands.

Jean-Michel Darrois, a lawyer for Prince Albert, confirmed to AFP that "offshore companies were indeed created in Panama in 1984 in the time of Rainier III".

But Albert II had "several times" asked his money manager to resolve the situation, "which he did not do", Darrois said.

"Since Palmero's replacement, all this is being liquidated."

Darrois said there had also been offshore companies set up in 2002 -- before Prince Albert's reign too -- in the UK overseas territory of the British Virgin Islands.

Palmero had for several years stopped paying fees on these.

This meant the firms had been struck off the registry and made it difficult for the royal family to claim what was rightfully theirs, he said.

'In their strictest interest'

But lawyer Marie-Alix Canu-Bernard, who represents the asset manager, said "Palmero never did anything without the knowledge of those employing him".

"Quite the contrary. It was always done in perfect agreement with them and in their strictest interest," she said.

It was not immediately clear why the royal family might place funds offshore as Monaco does not impose income or wealth tax on any of its nationals.

But sources close to the case say they might have hoped to prevent the press or anyone else from poking around in their financial affairs.

Monaco, the world's second-smallest country after the Vatican, has been ruled by the Grimaldi dynasty since 1297.

In recent decades its lack of tax and sunny climate have attracted many celebrities and wealthy individuals, and caused a real estate boom on the rocky outcrop of some two square kilometres (0.75 square miles).

Property sells for astronomical sums in the statelet.

According to official figures, the 88 new flats on sale in Monaco in 2022 went for a total of 1.2 billion euros ($1.3 billion).

Palmero was among four people close to Albert accused of schemes linked to property development in allegations posted on a website called the Dossiers du Rocher ("Rock Files") from 2021.

They have accused a property tycoon named Patrice Pastor -- who owns a large share of the market -- of being behind the website but he has strongly denied this.

Palmero, who had tried to curb Pastor's role in the sector, believes he convinced the prince to fire him.

'Confidential'

Since his dismissal, Palmero has tried and failed to sue the royal family through the Monaco legal system.

This month he filed a complaint with the European Court of Human Rights in Strasbourg, saying he had not received a fair trial in Monaco.

The ECHR is a court of the 46-member Council of Europe, to which Monaco belongs.

Palmero's lawyers Canu-Bernard and Christophe Llorca say he has also filed a complaint in Monaco against the royal family for "attempted extorsion and theft".

The royal family has in turn officially accused their former wealth manager of "breach of trust" and "stealing documents".

In its report, Le Monde described Palmero overseeing allowances for members of the royal household, including the prince's sisters Caroline and Stephanie and his wife Charlene and commenting on their expenses.

The Monaco-Matin newspaper in the statelet has accused Palmero of airing private matters in public.

But Palmero's lawyers defended him, saying he had told Le Monde that his notes -- handed over to Monaco authorities as part of another investigation -- were "confidential and not supposed to be shown".

The controversy comes after the Council of Europe last year warned Monaco over shortcomings in its anti-money laundering efforts.

Monaco on Friday said a new Monegasque Authority for Financial Security would start work this week to fight money laundering and other types of corruption.

© Agence France-Presse