Thousands of French demonstrators have taken to the streets in Paris to protest against the government's plan to extend the retirement age by one year.

Police say 28,000 people took part in a march from the Bastille through Paris' Right Bank on Thursday.

The one-day walkout by state workers involved mainly transport workers, as well as some other civil servants. It has been the latest one against a series of reforms by President Nicolas Sarkozy.

Jean-Jacques Lachelarde, one of the demonstrators, voiced his demands.

"I'm asking today that the government gives more to the employees who are enriching this country. The money should be invested in companies and not in the stock exchange. That's the message the government should understand."

Sarkozy, who took office a year ago on a vow to modernize France, faces more protests by teachers and students angry over job cuts.

Despite the pressure, Prime Minister Francois Fillon makes clear that the government will stand firm on the retirement reform. The plan requires workers to put in 41 years of full-time work instead of 40 to receive full state pensions.