Alitalia said a union threatened to tip the financially strapped airline into a tail spin after a wave of strikes that forced it to cancel hundreds of flights.

"We are in an extremely delicate phase," Alitalia wrote in half page advertisements in Italy's main newspapers on Thursday.

"The SULT, a union organization that represents several hundred flight attendants, carried out its latest strike yesterday, continuing to damage the company and threatening to push it back into (last year's) deep crisis."

Alitalia, which estimates 2004 losses of EUR850 million (USD$1.1 billion), declined to reveal on Thursday the cost of the latest round of strikes by the SULT, but union sources estimate damage in the millions of euros.

The SULT, undaunted, has warned it will continue to strike until Alitalia provides better terms for flight attendants than it gave in recent deals with the bigger unions, which bowed to salary cuts.

On Wednesday, Alitalia was forced to cancel 132 flights. Two other SULT strikes this year forced the state-controlled carrier to scrap more than 300 flights. The airline says it has an average of 540 flights departing from Italy every day.

"These (cancellations) have led to yet more lost revenues, vital for the company, but the real damage will be the loss of credibility with clients and investors," Alitalia said.

The company also reiterated its plans for a capital increase of up to EUR1.2 billion, which Alitalia needs to pay off debt and finance a restructuring that would spin off ground operations and eventually allow for fleet expansion.

It also warned that it would be ironic if it were ultimately sunk by the small SULT union instead of by troubles such as fuel prices and the heavy debt troubling the entire sector.

"It would be paradoxical to be defeated... just because a few people are being unreasonable," Alitalia said.

The SULT shrugged off the advertisements, saying that, if anything, they were a sign that the industrial action was sending a clear message to management.

"It's a confirmation that the strike was effective," SULT leader Fabrizio Tomaselli said. "We would hope that this same energy shown by the company (in the newspaper ads) is now put into the negotiations."