Saying he was "attentive" to the expressed concerns, the president reiterated the official retirement age would be prolonged by four months per year, reaching 62 in 2018.

People protest against the retirement reform in Paris, France, Sept. 7, 2010. French labor unions leading a nationwide strike against retirement reform hailed on Tuesday the success of the largest demonstration aimed at forcing the government to bow to the streets' call. About 2.5 million people participated in the strike across the country. [Ying Qiang/Xinhua]

"It's out of the question to return on this point," he insisted in his declaration.

Sarkozy said making French people work longer was the most reasonable way to solve the pension finance problem, and a new retirement age would be "the first axis of this reform."

The National Assembly, the lower house of French parliament, started examining the text of the reform bill on Tuesday.

Once the lower house passes the bill in a vote expected in late September, the bill will be subject to examination by the Senate in October.

An increased life span and growing unemployment in France have been creating a gaping hole in financing the pay-as-you-go pension system of the debt-burdened country for years.

Official data forecast the current system will record a deficit of 42.3 billion euros (53.6 billion U.S. dollars) in 2018, unless reformed.