France's ruling center-right government is in a tight corner after the revelation of alleged illegal political donation by L'Oreal heiress Liliane Bettencourt to support President Nicolas Sarkozy's election campaign.

France's Liliane Bettencourt leaves the Elysee Palace in Paris after a ceremony October 22, 2007. Liliane Bettencourt is the principal shareholder of L'Oreal, one of the world's leading cosmetics and beauty companies. [Xinhua/Reuters Photo]

The 55-year-old president is to address the nation via a television interview on Monday.

Some members of the opposition said Sarkozy is facing a system crisis.

"To get out of it, the president must act either by dissolving the National Assembly or announcing a profound reshuffle with a tightened government composed of faultless and indisputable people," Jerome Cahuzac, head of the parliamentary finance committee and a member of the opposition Socialist party, told the weekly Journal de Dimanche.

The Bettencourt affair first came to light when Bettencourt's former bookkeeper Claire Thibout unveiled recordings allegedly showing Bettencourt and Labor Minister Eric Woerth were involved in tax evasion.

Sarkozy and other members of the ruling UMP party, of which Woerth is also a member, backed the labor minister. A report from the tax inspectorate of the Finance Ministry on Sunday concluded that Woerth played no role in the tax affairs of the Bettencourts.

Woerth had been the campaign treasurer of Sarkozy.

The happenings took a new turn when accusations were pointed to the French president following a Mediapart web site report on the donation of 150,000 euros to finance Sarkozy's election campaign in 2007.

French weekly magazine Marianne reported last Friday that more than 390,000 euros (492,906 U.S. dollars) in cash had been withdrawn from Bettencourt's account in the four months before the 2007 election.

French law limits political donations to no more than 7,500 euros (9,478 dollars) per person per year, of which 150 euros (189 dollars) can be in cash.

Police are investigating Thibout's statement that the donations were made at the request of Bettencourt's wealth manager Patrice de Maistre, who denied the allegation.

Politicians said Sarkozy and other UMP members had backed Woerth to avoid Sarkozy himself coming under fire.

"I want to say that in supporting Eric Woerth, Sarkozy is protecting himself because if the role of Woerth is questioned it brings Sarkozy to questions too," said Benoit Hamon, spokesman of the Socialist Party.

The scandal is leading to a confidence crisis adding to economic woes such as tepid growth and high unemployment, amid angry voices calling for explanation and an immediate reshuffle.

"We are stuck in a crisis. There needs to be a reshuffle, and fast..." local media quoted Marie-Anne Montchamp, a UMP deputy, as saying.

Political analysts also said the scandal would primarily affect Sarkozy.

"The important electorate which Nicolas Sarkozy seized in 2007 risks abstention or may be attracted by the National Front or the opposition," said Roland Cayrol, head of research at the Center for Political Research at Sciences Po (Cevipof).

A recent survey by polling agency BVA showed Sarkozy's approval ratings fell to an all-time low of 33, making him one of the most unpopular French presidents since the indicator was started 30 years ago.

The survey showed 64 percent of the French people held negative opinions about Sarkozy, among which 31 percent thought him performed "very badly."

Another poll released last Friday said Sarkozy was doomed to lose the second round of the next election in 2012 to Socialist Party leader Martine Aubry.

Despite the need for a cabinet reshuffle, Sarkozy is likely to maintain the current government until this autumn, when he is expected to re-organize the UMP party and announce a ministerial reshuffle.

Some members of the opposition said they were doubtful whether the president's national address on Monday would help him.

"His words are worn due to regular use and facts which regularly denied what he said," said Cahuzac. "The last time Sarkozy made a TV address he assured the fall in jobless rate in the coming weeks but the figure soared. French people no longer believe him."