A planned strike by air traffic controllers and other public sector workers could disrupt French flights tomorrow, the DGAC civil aviation authority said.
Trade unions representing civil servants have issued strike notices to protest tomorrow against a pay offer from the government that was less than inflation.
"The impact of these strike notices on air traffic is currently difficult to foresee but disruptions are expected, especially at the start of the day," the DGAC said in a statement.
A DGAC official said the largest air traffic controllers' union had not called its members out to strike but that others had. Passengers should check with their airlines whether flights were on time, the aviation authority said.
The conservative government is trying to limit spending in efforts to cut its public sector deficit to within European Union limits, but risks triggering a wave of labour unrest if it leaves itself too little room for manoeuvre in pay talks.
Last October, hundreds of thousands of people demonstrated across France in a one-day strike over low pay, high unemployment and falling living standards but failed to win any major policy changes from the government.
Strikes are watched nervously by governments in France because street protests in 1995 are seen as having been responsible for the defeat of conservative Prime Minister Alain Juppe in snap elections two years later.
Prime Minister Dominique de Villepin's chances of remaining in power, and perhaps running for the presidency in an election due in 2007, rest heavily on his ability to push through reforms while simultaneously restoring the confidence of voters.