Ryanair pilots and flight attendants in Italy are to go on a four-hour strike on December 15, a union announced Wednesday, a threat shrugged off by the Irish airline.

The announcement comes after Ryanair management, which does not recognise any unions, declined to open negotiations concerning labour contracts with its Italian staff, the ANPAC union told AFP.

"The ANPAC representatives for pilots and flight assistants at Ryanair have asked the company to open negotiations so they can benefit from the branch agreement for Italian pilots," an ANPAC spokesman said.

"Ryanair's management has not even given a response and that is why the strike has been called," he said.

A Ryanair spokesman meanwhile told AFP in London that the carrier regularly received strike threats in Italy and Portugal.

"Both we and our pilots ignore these letters," he said.

"This is the sixth time FIT/CSIL or ANPAC has announced strikes by Ryanair pilots, only to postpone/cancel them later. We expect this latest threatened strike will also be postponed/cancelled since FIT/CSIL/ANPAC is an Alitalia union with no role in Ryanair", the spokesman said.