"If the strike continues tomorrow, border police, airport police and if necessary riot police... will be mobilised to ensure security at airports," Transport Minister Nathalie Kosciusko-Morizet said on Tuesday.
"It is very difficult in present conditions to scan and verify all passengers and luggage," she said.
Three hundred policemen and women and 100 gendarmes were already on standby to fill in for the strikers," interior ministry spokesman Pierre-Henry Brandet told AFP.
The strike was on launched Friday by unions demanding improved working conditions and salary increases. Negotiations on Sunday aimed at ending the strike failed.
By Tuesday evening, 430 of the 607 scheduled flights had taken off from Paris's Charles De Gaulle airport. All the flights from Lyon airport had taken off.