PARIS — French rail workers entered the eighth day of their nationwide strike to defend their hard-won retirement benefits on Nov. 21, buoyed by parallel strike actions by teachers, firefighters, utility workers, airport personnel, customs agents, tax inspectors, and weather service employees who walked out the day before in a dispute over proposed job cuts.

The transport workers strike is the largest nationwide labor battle in 12 years. Thousands of protesters took to the streets in support of the workers, and about half of the country’s public universities were shut down. Many high school students have also joined the solidarity actions.

French President Nicolas Sarkozy criticized the spreading strikes on Nov. 20, insisting he will not water down plans to cut the retirement benefits of public employees. Currently public employees can retire after working for 37.5 years; Sarkozy wants to increase that number to 40.

“France needs reforms to meet the challenges imposed on it by the world,” Sarkozy said in a speech to mayors. “These reforms have been too long in coming.” In recent days he has invoked the name of Margaret Thatcher, the notoriously anti-labor former British prime minister, as a positive example.

But the striking workers would have none of it.

Other issues are involved, too. The French have become increasingly concerned about their diminishing purchasing power. At least 48 percent of the population now cites their pay or income as their number one worry.

When Sarkozy was campaigning for president, he said his goal was not merely to keep purchasing power stable, but to increase it. Polls show that nearly three-quarters of the population believes his government has failed to deliver on this promise.

Sarkozy’s popularity has declined from 71 percent three weeks ago to 51 percent today, according to another poll.

The French Communist Party, during its election campaign earlier this year, called for increasing the minimum wage and boosting welfare benefits. It also called for a hike in the wages of the country’s public workers.

The French rail workers were also heartened by the giant strike by German transportation workers, which continues to paralyze much of Germany’s rail traffic.

Talks with the French transport unions were to start Nov. 21 and the government said state representatives would take part.

The CGT union federation estimated 700,000 people joined protest marches around France on Nov. 20 in defense of the civil service.

At a demonstration in Paris, the “Internationale” song of working-class solidarity blared from loudspeakers and marchers chanted “All as one!” They marched across the Left Bank to the gold-domed monument at Les Invalides, site of Napoleon’s tomb.

National newspapers were absent from kiosks as printers and distributors jumped on the strike bandwagon. Strike-hit France-Inter radio broadcast music and a message of apology instead of regular programming.

The Associated Press, L’Humanité and Mike Tolochko contributed to this story.