The country's labor unions expected 244 protests across the country. The Interior Ministry said 500,000 protestors took part in the strike at the noon.

Protesters gather at the Bastille Square to protest against President Nicolas Sarkozy's plan to raise the retirement age up to 62 in Paris, France, Oct. 12, 2010. Protesters walk near the Bastille Square to protest against President Nicolas Sarkozy's plan to raise the retirement age up to 62 in Paris, France, Oct. 12, 2010. [Xinhua/Zhang Yina]

The Senate even suspended its review of the pension reform bill for a while in the afternoon as some left-wing senators took part in the demonstration, according to local media.

French landmark the Eiffel Tower was reported closed to the public in the afternoon due to a strike by staff.

"The participation is increasing. This demonstration is exceptional compared to other days of strikes," Bernard Thibault, head of CGT trade union, told local RTL radio.

Despite the pressure, French Prime Minister Francois Fillon ruled out any new concessions and criticized the opposition as "irresponsible" for involving high school students in the demonstration.

According to the Education Ministry, some 360 French high schools stopped teaching due to the strike, while 22 percent of teachers joined the Tuesday walkout. Youngsters were observed among street protestors.

"We know that this reform wouldn't be easily accepted by the citizens. We listen and we understand their concerns," Fillon told senators, but stressing the government had gone as far as it could in amending the bill.

A CSA survey issued Monday showed that 69 percent of the French people backed the strike, with 61 percent in favor of more open-ended industrial actions.

Trade unions announced another strike for Saturday.

The government wants to extend the minimum age at which state-funded pensions are available among other measures aimed at reducing its budget deficit.