PARIS — Travel woes piled up in France with air traffic delays adding to a week of rail strikes as many of the nation’s 5 million civil servants held a day-long walkout Tuesday in the biggest test of President Nicolas Sarkozy’s appetite for reform.

Schools and the postal service were among victims of the day of action by civil servants pressing for pay hikes and assurances of job security. More than 300,000 — or nearly 40 percent — of France’s teachers stayed off the job, the Education Ministry said, forcing some schools to close. Flights also were delayed and newspapers not printed.

A small minority of the work forces at France’s two main energy utilities, Electricite de France and Gaz de France, joined the strike, the companies said.

Although civil servants and transport workers have different demands, together their protests are the biggest test to Sarkozy’s promises of reform and cost-cutting since he took office in May.

National newspapers couldn’t be found at kiosks Tuesday as printers and distributors jumped on the strike bandwagon, much like students angry about university reforms adopted last summer.

Striking air traffic controllers caused delays averaging 45 minutes at Paris’ two airports, Charles de Gaulle and Orly, on flights from short domestic routes to long-haul.

Despite the increased pressure on Sarkozy, the government has stood firm. Prime Minister Francois Fillon said Monday that reforms must move forward.

Tuesday marked the seventh day of transport strikes, which have caused massive disruption on the national rail network and in Paris’ Metro and commuter lines.

Budget Minister Eric Woerth told France Inter radio on Tuesday that those strikes could impact France’s economic growth if they last. The government says they are costing France’s economy between $440 million and $513 million a day.

Train drivers are protesting Sarkozy’s plans to extend the number of years they must work before retiring. The government has insisted that for talks to start, more strikers must return to work. It also says that the core of the reform — that all workers will have to work for 40 years to qualify for full pensions — is nonnegotiable.

The conservative president, who has often jumped into disputes to sort them out himself, has remained curiously silent about the strike — seemingly to avoid stoking the protesters’ determination.

Sarkozy was elected in May on promises to reform France — from its courts to its creaking university system, its army of civil servants to rail workers whose special retirement privileges he vowed to erase.

Campuses are also bubbling with discontent. Knots of students have been blocking classes at dozens of France’s 85 state-run universities to protest a law allowing them to seek nongovernment funding. Critics fear the change will mean schools closing their doors to the poor and scrapping classes that can’t attract private funding.

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Associated Press writer Jean-Marie Godard contributed to this story.