French flag-carrier Air France warned that it would cancel 35 percent of its long-haul flights and 25 percent of shorter journeys Thursday as an aviation workers' strike went on for a fourth day.

About the same number of flights were cancelled on the third day of the strike on Wednesday, the airline said.

Air France, the firm the worst hit by the industrial action, urged customers to postpone travel and sent out tens of thousands of emails and text messages to clients warning them their flights had been cancelled or delayed.

The strike by workers including pilots, flight attendants and ground staff hit services at Paris's Charles de Gaulle airport, a global aviation hub, as well as several French regional airports.

Unions called the four-day strike to protest against a draft law that would require aviation workers to individually give 48 hours notice prior to striking, saying this limits labour rights.

The bill was approved by France's lower house last month and is due to be debated in the Senate.

The head of the SNPL pilots' union, Yves Deshayes, said the union would meet with transport ministry officials on Friday and then decide whether to pursue further strike action against the bill.

"Depending on the proposals made we will decide whether to continue the strike or not," he said, adding that industrial action could take place during France's February school holidays.

But Transport Minister Thierry Mariani said the government would not drop the bill, which he said was aimed at protecting passengers' rights.

"It is out of the question that we move on this text because it is not only useful but indispensable," he told AFP. "French policy is decided in parliament and not in a union headquarters."

Unions said more than 60 percent of pilots were participating in the strike but Air France said only 30 percent of pilots and 15 percent of flight attendants were taking part.

burs/mm/dc/co